Switch LE HS when a play command comes from LE HS

LeAudioService.setActiveDevice() should be set and the active device
of A2dpService should be reset in order to switch to LE HS when a
play key event comes from LE HS.

Bug: 228909271
Tag: #refactor
Test: atest BluetoothInstrumentationTests
     (atest GoogleBluetoothInstrumentationTests:MediaControlGattServiceTest)
Change-Id: I537daf3c05c48a109a8d5a550c57a80bcca1e8c0