Remove release notes item about publication intructions

RELEASENOTES.md

@@ -71,8 +71,6 @@
     *   Upgrade IMA SDK dependency to 3.23.0, fixing an issue with
         `NullPointerExceptions` within `WebView` callbacks
         ([#8447](https://github.com/google/ExoPlayer/issues/8447)).
-*   Update instructions and publishing configuration for releasing to Google's
-    Maven repository instead of bintray/JCenter.
 *   FFmpeg extension: Fix playback failure when switching to TrueHD tracks
     during playback ([#8616](https://github.com/google/ExoPlayer/issues/8616)).