ruby: backport final JIT review fixes to deployed LuaJIT omnibus

[dalehamel]

Purpose

Create a regression-testing copy of the currently deployed LuaJIT omnibus and backport only the final two Ruby JIT review fixes. PR #50 itself remains unchanged.

Verified deployed base

The production chain resolves to the same exact profiler revision:

1. container-os-tools-shopify production manifest uses Prophiler image e22944afb0c0e03641728a5e56188dd49ab6e2e3.
2. That profiles-processor commit pins ebpf-profiler/opentelemetry-ebpf-profiler and lib/otel-errors EXPECTED_COMMIT to 7c16777d686d62553714456f9ca8dfbfcb6a5fa8.
3. 7c16777d is the current head of LuaJIT unwinding — omnibus snapshot (tarantool + openresty, amd64/arm64) #50 (dale/luajit-omnibus).
4. Live cos-toolbox-shopify DaemonSets sampled across core-us, core-eu, and apps-us use immutable image digest sha256:606d8720…; Artifact Registry maps that digest to tag e22944af…. All desired pods use that digest (core-us 824/824 ready; the other sampled fleets were fully updated with one node each in ordinary readiness churn).

This PR is based directly on 7c16777d. It does not merge or rebase upstream main; that synchronization is intentionally deferred.

Backports

Exactly two source commits are added:

• ruby: bound unlabeled JIT fallback to executable mappings
  • Keeps exact PR_SET_VMA-named reservations, including non-executable VMAs.
  • Bounds unlabeled fallback at the observed anonymous-executable envelope instead of absorbing an ambiguous trailing RW/PROT_NONE mapping.
  • Still spans non-executable holes between observed executable fragments.
• ruby: report partial JIT mapping publication
  • Preserves proc-data-before-prefix ordering.
  • Adds explicit context when prefix publication fails after proc data is already visible, and verifies retry behavior.

No generated ABI types, error catalog, eBPF source, or eBPF blobs changed.

Validation

• Linux arm64 unit and race tests passed for process, processmanager, interpreter/ruby, and hermetic interpreter/luajit tests.
• Ruby 3.4.7 YJIT coredump regression tests passed on arm64 and amd64.
• A live privileged arm64 OpenResty/LuaJIT fib integration test passed with resolved Lua frames (2 passing traces, 0 failures).
• The committed amd64 and arm64 eBPF blob hashes are byte-identical to LuaJIT unwinding — omnibus snapshot (tarantool + openresty, amd64/arm64) #50.
• git diff --check passed.