fix: enhance StartK8sStreamWithHeartBeat to prevent goroutine leaks and improve error handling

[Ash-exp]

Description

Fixes https://github.com/devtron-labs/sprint-tasks/issues/2893

Checklist:

• The title of the PR states what changed and the related issues number (used for the release note).
• Does this PR requires documentation updates?
• I've updated documentation as required by this PR.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have tested it for all user roles.
• I have added all the required unit/api test cases.

Does this PR introduce a user-facing change?

Summary by Bito

• Added import for async.Runnable from common-lib to enable enhanced goroutine management.
• Modified PumpImpl struct to include asyncRunnable field and updated constructor to accept it.
• Implemented sync.Once for idempotent stream closing in StartK8sStreamWithHeartBeat method.
• Used sync.WaitGroup to synchronize heartbeat goroutine exit, ensuring function returns only after goroutine completes.
• Wrapped heartbeat goroutine in asyncRunnable.Execute for panic recovery and metrics collection.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud