[controller] Refactor push job details handling into PushJobDetailsMa…

[eldernewborn]

What changed and why

This PR extracts push-job-details read/write responsibilities from VeniceHelixAdmin into a dedicated PushJobDetailsManager class to improve separation of concerns and maintainability.

Before this change, VeniceHelixAdmin owned:

• push job details RT topic lookup/retry logic
• schema-id lookup for system-store writes
• lazy writer/client initialization
• push job details and batch heartbeat store read paths

After this change, those responsibilities are encapsulated in PushJobDetailsManager, while VeniceHelixAdmin delegates to it.

How this is implemented

• Added services/venice-controller/src/main/java/com/linkedin/venice/controller/PushJobDetailsManager.java
  • Owns push-job-details serializer, RT topic checks, schema-id resolution (local leader and remote controller path), writer lifecycle, and store client lifecycle.
• Updated services/venice-controller/src/main/java/com/linkedin/venice/controller/VeniceHelixAdmin.java
  • Replaced inline push-job-details logic with delegation to PushJobDetailsManager.
  • Updated close path to close manager-owned resources.
  • Preserved push-job metrics emission in VeniceHelixAdmin before delegating write.
• Added unit tests in services/venice-controller/src/test/java/com/linkedin/venice/controller/PushJobDetailsManagerTest.java
  • Covers happy path, retry/failure cases, local vs remote schema-id resolution, lazy client initialization, exception wrapping, and close behavior.

Behavior/compatibility notes

• No protocol/schema changes introduced.
• No API contract changes intended.
• Refactor only; behavior is intended to remain equivalent.

Testing performed

• Targeted unit test:
  • ./gradlew :services:venice-controller:test --tests com.linkedin.venice.controller.PushJobDetailsManagerTest
• Coverage verification for changed submodule:
  • ./gradlew :services:venice-controller:jacocoTestCoverageVerification

Both commands passed locally.

Checklist

• GitHub issue linked (if non-trivial): Resolves #<issue_number>
• Tests added/updated for changed behavior
• No new dependency introduced
• Documentation impact reviewed (no user-facing doc changes required)
• Contribution is my original work and I license it under the project’s open source license