[Backport 3.0] Fix Flaky RemoteSplitIndexIT (#15107)

[opensearch-trigger-bot]

Backport 93d5356 from #18329.

[github-actions]

❕ Gradle check result for 2a4a575: 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.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.53%. Comparing base (ea48ab0) to head (2a4a575).
Report is 6 commits behind head on 3.0.

Additional details and impacted files

@@             Coverage Diff              @@
##                3.0   #18330      +/-   ##
============================================
- Coverage     72.55%   72.53%   -0.03%     
+ Complexity    67201    67158      -43     
============================================
  Files          5480     5480              
  Lines        310322   310322              
  Branches      45140    45140              
============================================
- Hits         225162   225086      -76     
- Misses        66748    66827      +79     
+ Partials      18412    18409       -3     

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