Fix CHANGELOG on main (#6183)

Three changes here:
 - Remove unneeded entry (was removed in backport) (#6049)
 - Move segrep change to proper section (was put in correct spot in
   backport) (#6122)
 - Add back issue that was merged to main prior to 2.5 release but not
   backported, and was therefore removed from the main CHANGELOG (#4603)

Signed-off-by: Andrew Ross <andrross@amazon.com>

CHANGELOG.md

@@ -68,7 +68,6 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix 'org.apache.hc.core5.http.ParseException: Invalid protocol version' under JDK 16+ ([#4827](https://github.com/opensearch-project/OpenSearch/pull/4827))
 - Fixed compression support for h2c protocol ([#4944](https://github.com/opensearch-project/OpenSearch/pull/4944))
 - Support OpenSSL Provider with default Netty allocator ([#5460](https://github.com/opensearch-project/OpenSearch/pull/5460))
-- Segment Replication - Fixed bug where inaccurate sequence numbers were sent during replication ([#6122](https://github.com/opensearch-project/OpenSearch/pull/6122))
 
 ### Security
 
@@ -82,7 +81,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Replace latches with CompletableFutures for extensions ([#5646](https://github.com/opensearch-project/OpenSearch/pull/5646))
 - Add GeoTile and GeoHash Grid aggregations on GeoShapes. ([#5589](https://github.com/opensearch-project/OpenSearch/pull/5589))
 - Add support to disallow search request with preference parameter with strict weighted shard routing([#5874](https://github.com/opensearch-project/OpenSearch/pull/5874))
-- Changing ExtensionActionRequest streaminput constructor to be public ([#6094](https://github.com/opensearch-project/OpenSearch/pull/6094))
+- Added support to apply index create block ([#4603](https://github.com/opensearch-project/OpenSearch/issues/4603))
 - Adds support for minimum compatible version for extensions ([#6003](https://github.com/opensearch-project/OpenSearch/pull/6003))
 
 ### Dependencies
@@ -108,6 +107,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Fixed
 - [Segment Replication] Fix for peer recovery ([#5344](https://github.com/opensearch-project/OpenSearch/pull/5344))
 - Fix weighted shard routing state across search requests([#6004](https://github.com/opensearch-project/OpenSearch/pull/6004))
+- [Segment Replication] Fix bug where inaccurate sequence numbers are sent during replication ([#6122](https://github.com/opensearch-project/OpenSearch/pull/6122))
 
 ### Security