Remove broadcastMetadata trigger.

On some devices the play/pause status would go through an extra
transition due to the value provided by the Media Browse Service not
being in line with the actual state.  By eliminating that state we
eliminate the race condition.

Bug: 74605206
Test: runtest bluetooth -p com.android.bluetooth.a2dpsink

(cherry picked from commit 3a3d34fa)

Change-Id: I53e4a11636dc798e69e8229bf48db0617cf4dbce