[test] Unstable test CoordinatorEventManagerTest.testMetricsUpdatedImmediatelyOnStartup

[github-actions]

https://github.com/apache/fluss/actions/runs/25341954615/job/74301223294

[ERROR] org.apache.fluss.server.coordinator.event.CoordinatorEventManagerTest.testMetricsUpdatedImmediatelyOnStartup  Time elapsed: 67.301 s  <<< FAILURE!
org.opentest4j.AssertionFailedError: 

[wuchong]

another instance: https://github.com/apache/fluss/actions/runs/25358084556/job/74351435000

[wuchong]

This may have been fixed by #3210. Let's watch some time and close this if not happen again.

[wuchong]

I checked that https://github.com/apache/fluss/actions/runs/25358084556/job/74351435000 is ran after #3210 is merged, thus the fix of #3210 doesn't work. @swuferhong could you take a look at this issue?

[swuferhong]

I checked that https://github.com/apache/fluss/actions/runs/25358084556/job/74351435000 is ran after #3210 is merged, thus the fix of #3210 doesn't work. @swuferhong could you take a look at this issue?

Ok, I will take a look.