Revert "Always send KEYCODE_MEDIA_PLAY_PAUSE"

Due to double debounce delays in the media framework as well as Google Play Music (to enable double-tap-to-skip feature), this introduces a delay in switching play state.

Reverting for now and will focus on synchronizing play state instead.

This reverts commit 31f04fc1.

Bug: 64006398 
Fixes: 67853947
Change-Id: I1c866906726c19e12de869c9ccdea6d06b069291