Update changelog

Signed-off-by: Matt Provost <provomat@amazon.com>

Author: BSFishy

CHANGELOG.md

@@ -24,6 +24,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Reduce the amount of comments in compiled CSS ([#4648](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4648))
 - [Saved Object Service] Customize saved objects service status ([#4696](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4696))
 - [Discover] Update styles to compatible with OUI `next` theme ([#4644](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4644))
+- Remove visualization editor sidebar background ([#4719](https://github.com/opensearch-project/OpenSearch-Dashboards/pull/4719))
 
 ### 🐛 Bug Fixes