BluetoothAudio HAL: flip to be enabled by default on P19

Swap audio XML files, and supports following scenarios:
1) (default) audio_policy_configuration.xml
   Using BluetoothAudio HAL and A2DP offload
2) audio_policy_configuration_a2dp_offload_disabled.xml
   Using BluetoothAudio HAL only when A2DP offload is 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
Change-Id: I86a8fc4de81b1b103cc39b65938bc97c65bd3a3a
5 files changed