Replace fixed sleep delays with active polling in prometheus service test

[sashaodessa]

Description:

What type of PR is this?

Bug fix

What does this PR do? Why is it needed?

Replaces fixed time.Sleep(time.Second) delays in TestLifecycle with active polling to wait for service readiness/shutdown. This improves test reliability and reduces execution time by eliminating unnecessary waits when services start/stop faster than expected.

Which issues(s) does this PR fix?

N/A - Minor test improvement

Other notes for review

• Uses 50ms polling interval with 3s timeout for both startup and shutdown checks
• Maintains same test logic while making it more efficient and less flaky
• No functional changes to the service itself

Acknowledgements

• I have read CONTRIBUTING.md.
• I have included a uniquely named changelog fragment file.
• I have added a description to this PR with sufficient context for reviewers to understand this PR.

[prestonvanloon]

LGTM. Please add a changelog fragment if you want this PR to merge. Thanks!

[sashaodessa]

@prestonvanloon added a changelog fragment

[sashaodessa]

@prestonvanloon any updates?