i18n(ja): fix defects found in dedicated review of large reference files

[yahonda]

What is changed, added or deleted? (Required)

This PR fixes genuine translation defects found in a dedicated 1:1 review (against the English source) of 7 large top-level files that had never previously gotten a dedicated defect-review round: system-variables.md, tikv-configuration-file.md, pd-control.md, optimizer-hints.md, sql-tuning-best-practice.md, sql-plan-management.md, latency-breakdown.md.

sql-tuning-best-practice.md had zero genuine defects. The other 6 files needed fixes:

• optimizer-hints.md: 3 hint-name/placeholder headings were translated as Japanese prose instead of kept as the literal identifier (STRAIGHT_JOIN(), RESOURCE_GROUP(resource_group_name), SET_VAR(VAR_NAME=VAR_VALUE)), inconsistent with every sibling heading in the file; plus one dropped に particle.
• tikv-configuration-file.md: 6 sites using the HTML entity > where EN uses a literal > (or \> in one MDX-escaped case), missed by the earlier corpus-wide entity sweep since this file wasn't included in it.
• pd-control.md: 8 dropped は particles (a code-span subject followed by a bare comma instead of は before the verb, breaking 8 config-option descriptions), plus one mistranslation from a garden-path reading of an awkward EN sentence ("factors in" parsed as a noun instead of a verb).
• sql-plan-management.md: a dropped は particle, an ungrammatical ずつ usage, a missing colon before a trailing code span, a missing "/" between PREPARE and EXECUTE (2 occurrences), and 3 more > entity-vs-literal mismatches on one line.
• latency-breakdown.md: the term "PointGet" was inconsistently rendered (獲得中/取得中/バッチPointGet) in 3 places instead of matching this file's own heading convention of keeping PointGet / Batch PointGet in English; plus one verb-to-noun fix for parallel list structure (提案する → 提案, matching コミット/適用).
• system-variables.md: two duplicated-word typos (照合照合順序 → 照合順序); a genuine Scope/Range label collision affecting 126 variable entries where both the Scope field and a numeric Range field were labeled "範囲:" in the same entry, making them indistinguishable (unified the Scope label to the file's own already-used alternate "対象範囲：" only where it collided with a Range field); 18 zero-width-space (U+200B) MT artifacts removed; 2 dropped が/を particles; one value description rephrased from an imperative command to a declarative description, matching EN's phrasing.

All changes verified against the English source (release-8.5 branch) line by line; line counts preserved in every file.

Which TiDB version(s) do your changes apply to? (Required)

• i18n-ja-release-8.5 (TiDB Japanese documentation for TiDB 8.5 versions)

What is the related PR or file link(s)?

• This PR is translated from:
• Other reference link(s):

AI agent involvement

• The changes in this PR were primarily made by an AI agent on behalf of the PR author.

Do your changes match any of the following descriptions?

• Delete files
• Change aliases
• Need modification after applied to another branch
• Might cause conflicts after applied to another branch

Summary by CodeRabbit

• Documentation
  • Improved Japanese wording, terminology, grammar, punctuation, and formatting across latency, optimizer hints, PD controls, SQL plan management, system variables, and TiKV configuration references.
  • Clarified explanations for query binding, automatic plan capture, configuration scopes, optimizer behavior, and related settings.
  • Corrected displayed markup without changing functionality, configuration semantics, metrics, commands, or available system variables.

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📝 Walkthrough

Walkthrough

Japanese documentation wording, terminology, scope labels, SQL Plan Management descriptions, and HTML entity rendering were corrected across six Markdown files. Product behavior, metrics, configuration semantics, and system variables were not changed.

Changes

Japanese documentation updates

Layer / File(s)	Summary
Terminology and grammar corrections latency-breakdown.md, optimizer-hints.md, pd-control.md	Corrected Japanese wording and standardized latency, optimizer hint, and PD control terminology.
SQL Plan Management wording sql-plan-management.md	Clarified binding creation, normalization, replacement, query targeting, removal, precedence, historical plans, automatic capture, upgrades, and baseline evolution.
System-variable scope and terminology system-variables.md	Normalized scope labels and corrected terminology across system-variable entries.
System-variable behavior descriptions system-variables.md	Clarified transaction, concurrency, plan-cache, executor, and related variable descriptions.
Optimizer and runtime variable documentation system-variables.md	Updated optimizer, statistics, TiFlash, sharding, timeout, and slow-log descriptions.
TiKV configuration markup tikv-configuration-file.md	Replaced escaped greater-than entities with literal characters in five descriptions.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: 🔵 Low · up to a101f

This documentation-only PR corrects Japanese translation defects and is mergeable with owner follow-up for localized Markdown formatting issues: one code fence may render outside its list item, and several changed list markers are flagged by documentation linting.

Possibly related PRs

• pingcap/docs#23581: Updates related SQL Plan Management terminology and SQL statement normalization wording.

Suggested labels: area/develop

Suggested reviewers: qiancai

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly identifies Japanese internationalization fixes found during a focused review of large reference files.
Description check	✅ Passed	The description explains the changes, affected files, review basis, target documentation branch, and AI involvement; blank reference links are non-critical.

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests

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Actionable comments posted: 4

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📒 Files selected for processing (6)

• latency-breakdown.md
• optimizer-hints.md
• pd-control.md
• sql-plan-management.md
• system-variables.md
• tikv-configuration-file.md

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Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (2)

pd-control.md (2)

1115-1115: 📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

Use the same scheduling expression for write-peer-priorities.

Line 1115 uses 「ホットリージョンのスケジュールにおいて」, while the two preceding entries use 「ホットリージョンをスケジューリングする際に」. Use the same construction for all three priority settings.

Committable replacement

    -   `write-peer-priorities`は書き込みピアタイプのホットリージョンをスケジューリングする際に、スケジューラがどのディメンションを優先するかを制御します。ディメンションのオプションは`byte`と`key`です。

As per path instructions: “For every actionable issue, provide a GitHub committable suggestion block containing the exact replacement text whenever the fix can be safely and completely applied to contiguous lines in the diff.”

Source: Path instructions

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219-219: 📐 Maintainability & Code Quality | 🔵 Trivial | 💤 Low value

Use consistent scheduling terminology for write-peer-priorities.

    -   `write-peer-priorities`は書き込みピアタイプのホットリージョンをスケジューリングする際に、スケジューラがどのディメンションを優先するかを制御します。ディメンションのオプションは`byte`と`key`です。

Source: Path instructions

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📒 Files selected for processing (4)

• latency-breakdown.md
• pd-control.md
• sql-plan-management.md
• system-variables.md

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[LGTM Timeline notifier]

Timeline:

• 2026-08-20 11:11:34.20788688 +0000 UTC m=+154529.378980994: ☑️ agreed by qiancai.