[FLUSS-2473][server][test] Fix flaky test FlussAuthorizationITCase.testRebalance

[ZuebeyirEser]

Purpose

Linked issue: close #2473

Brief change log

This PR fixes the flaky test FlussAuthorizationITCase.testRebalance.

The error happens because of a race condition between creating a table and the rebalance operation. Sometimes, RebalanceManager tries to build a cluster model while a table is still being created. In this specific moment, the table has a Leader elected, but the replica list is not updated yet. This caused the error RebalanceFailureException: Leader replica is not in the bucket.

Tests

• Added testRebalanceDuringConcurrentTableCreation in FlussAuthorizationITCase.
• I ran the new test locally more than 50 times and it passed. Before the fix, it failed consistently.
• I also ran the full Maven build locally and all tests passed.

API and Format

no

Documentation

no