When the player finishes playback and reaches the STATE_ENDED,
the notification remains visible with a pause button and the
service is kept in the foreground. This is a bug.
With this change, when the player reaches the STATE_ENDED, the
service is stopped from the foreground and a notification is shown
with a play button. If the play icon is tapped, the player will restart
playback of the last played item. Playing the last played item again
is the existing behavior when play/pause commands are received from
the legacy MediaSession (e.g. BT headset buttons).
#minor-release
Issue: google/ExoPlayer#112
PiperOrigin-RevId: 467231509
