[CI] Optimize port cleanup logic

[EmmonsCurse]

Motivation

Optimize the port cleanup logic used in CI coverage testing.
Previously, stale processes occupying ports occasionally caused test container startup failures.
This PR improves the cleanup reliability and clarity of port handling.

Modifications

1. Refactored the port cleanup script for better readability and safety.
2. Added detailed logging to track which ports and PIDs are cleared.
3. Ensured the cleanup runs before each coverage job to prevent port conflicts.

Usage or Command

No user-facing command changes.

Accuracy Tests

N/A – this change only affects CI

Checklist

• Add at least a tag in the PR title.
  • Tag list: [[FDConfig],[APIServer],[Engine], [Scheduler], [PD Disaggregation], [Executor], [Graph Optimization], [Speculative Decoding], [RL], [Models], [Quantization], [Loader], [OP], [KVCache], [DataProcessor], [BugFix], [Docs], [CI], [Optimization], [Feature], [Benchmark], [Others], [XPU], [HPU], [GCU], [DCU], [Iluvatar], [Metax]]
  • You can add new tags based on the PR content, but the semantics must be clear.
• Format your code, run pre-commit before commit.
• Add unit tests. Please write the reason in this PR if no unit tests.
• Provide accuracy results.
• If the current PR is submitting to the release branch, make sure the PR has been submitted to the develop branch, then cherry-pick it to the release branch with the [Cherry-Pick] PR tag.

[paddle-bot]

Thanks for your contribution!