AudioPlaybackConfiguration: prevent race condition on mIPlayerShell

Synchronize changes to mIPlayerShell after release of corresponding
  player.
Flush binder commands when a player is released, in AudioService
  and in the clients that have an AudioPlaybackCallback implementation.
  Do the same in MediaSessionService, which directly implements
  the IPlaybackConfigDispatcher interface, without going through
  the AudioPlaybackCallback registration and notification
  mechanisms.

Test: adb shell /system/bin/write_sine_callback -m2 -pl
Bug: 65450109
Change-Id: I2f0697e0e164283284ce30d2cc736c4f8df270c4