Reland BluetoothAudio HAL: flip to be enabled by default

Change to new properties + swap audio XML files, and supports following
scenarios:
1) (default) audio_policy_configuration.xml
   Using BluetoothAudio HAL (+ A2DP offload if supported)
2) audio_policy_configuration_a2dp_offload_disabled.xml
   Using BluetoothAudio HAL only when A2DP offload is supported but
   disabled.
3) audio_policy_configuration_bluetooth_legacy_hal.xml
   No BluetoothAudio HAL nor A2DP offload

Bug: 126304229
Test: Switch BluetoothAudio HAL and A2DP offload manully
(cherry picked from commit baa9e4e1)

Change-Id: I3c17b304a12c1eccd9f97ee50a0b7cf6e4b9a1da