stopInternal should release MediaSource

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=176763841

library/core/src/main/java/com/google/android/exoplayer2/ExoPlayerImplInternal.java

@@ -766,7 +766,7 @@ import java.io.IOException;
   }
 
   private void stopInternal() {
-    resetInternal(/* releaseMediaSource= */ false, /* resetPosition= */ false);
+    resetInternal(/* releaseMediaSource= */ true, /* resetPosition= */ false);
     loadControl.onStopped();
     setState(Player.STATE_IDLE);
   }