Fix CloseIndexIT test (#18946)

* Fix CloseIndexIT test

Signed-off-by: Atri Sharma <atri.jiit@gmail.com>

* Add CHANGELOG entry

Signed-off-by: Atri Sharma <atri.jiit@gmail.com>

* Fix spotless issues

Signed-off-by: Atri Sharma <atri.jiit@gmail.com>

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Signed-off-by: Atri Sharma <atri.jiit@gmail.com>

Author: atris

CHANGELOG.md

@@ -98,6 +98,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Removed
 
 ### Fixed
+- Fix flaky tests in CloseIndexIT by addressing cluster state synchronization issues ([#18878](https://github.com/opensearch-project/OpenSearch/issues/18878))
 - Add task cancellation checks in aggregators ([#18426](https://github.com/opensearch-project/OpenSearch/pull/18426))
 - Fix concurrent timings in profiler ([#18540](https://github.com/opensearch-project/OpenSearch/pull/18540))
 - Fix regex query from query string query to work with field alias ([#18215](https://github.com/opensearch-project/OpenSearch/issues/18215))