[Fix Bug] Allocation and Rebalance Constraints of WeightFunction are incorrectly reset

[guojialiang92]

Description

This PR reproduced the issue (#[13429]) in Test SegmentReplicationAllocationIT#testSingleIndexShardAllocation. Without this fix, the test will fail consistently.

This issue was raised a year ago but has never been fixed. We also encountered the same issue in the segment replication scenario with primary shard balance enabled, and have fixed it.

Related Issues

Resolves #[13429]

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

✅ Gradle check result for f57aadd: SUCCESS

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.06%. Comparing base (006a53f) to head (af9a7d6).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #19012      +/-   ##
============================================
+ Coverage     73.05%   73.06%   +0.01%     
- Complexity    70627    70639      +12     
============================================
  Files          5723     5723              
  Lines        323489   323493       +4     
  Branches      46851    46851              
============================================
+ Hits         236311   236368      +57     
+ Misses        68174    68057     -117     
- Partials      19004    19068      +64     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[opensearch-trigger-bot]

This PR is stalled because it has been open for 30 days with no activity.

[github-actions]

❌ Gradle check result for 17a9dd3: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❕ Gradle check result for 72ab29b: UNSTABLE

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[kkewwei]

Overall, there are no major issues. There's a minor point to consider: should we add unit tests in BalancedShardsAllocatorTests, or would it be more appropriate to add them in LocalShardsBalancerTests?

[github-actions]

✅ Gradle check result for af9a7d6: SUCCESS