AudioService: do not mute music systematically in setBluetoothA2dpOn

Only mute music if an actual change in Bluetooth A2DP state happens
when setBluetoothA2dpOn() is called.

Bug: 334182057
Test: repro steps in bug.
Change-Id: If2494dc9db1252cf1afb6ffcd600553b8140a191
Merged-In: If2494dc9db1252cf1afb6ffcd600553b8140a191
1 file changed