AudioDeviceBroker: mute call when switching HFP device

When a Bluetooth HFP device is disconnected as part of a device switch
and SCO audio is connected, mute call until either BT SCO audio is reconnected
or a 2 second timeout happens.

Bug: 385816977
Test: repro steps in bug
Flag: com.android.media.audio.optimize_bt_device_switch
Change-Id: I77c2f5bdd4c5f8434cbd641d137584427be6b10a