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 86950ad2.

Bug: 64006398 
Change-Id: Ib314da388c85af5dfb66326802ab062a32c52792
Fixes: 67853947