Remove unneeded release notes.

PiperOrigin-RevId: 405626270

Author: Samrobbo

RELEASENOTES.md

@@ -16,8 +16,6 @@
         `com.google.android.exoplayer2.decoder.CryptoException`.
     *   Move `com.google.android.exoplayer2.upstream.cache.CachedRegionTracker`
         to `com.google.android.exoplayer2.upstream.CachedRegionTracker`.
-    *   Make `ExoPlayer.Builder` return a `SimpleExoPlayer` instance.
-    *   Deprecate `SimpleExoPlayer.Builder`. Use `ExoPlayer.Builder` instead.
     *   Remove `ExoPlayerLibraryInfo.GL_ASSERTIONS_ENABLED`. Use
         `GlUtil.glAssertionsEnabled` instead.
     *   Move `Player.addListener(EventListener)` and