Remove un-necessary changelog entry (#15781)

Signed-off-by: Harsha Vamsi Kalluri <harshavamsi096@gmail.com>

Author: harshavamsi

CHANGELOG.md

@@ -5,7 +5,6 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## [Unreleased 2.x]
 ### Added
-- MultiTermQueries in keyword fields now default to `indexed` approach and gated behind cluster setting ([#15637](https://github.com/opensearch-project/OpenSearch/pull/15637))
 
 ### Dependencies
 - Bump `com.azure:azure-identity` from 1.13.0 to 1.13.2 ([#15578](https://github.com/opensearch-project/OpenSearch/pull/15578))