Use BluetoothAudio HAL 2.0 for Pixel 1, 2

When ro.bluetooth.a2dp_offload.supported is false, but
persist.bluetooth.bluetooth_audio_hal.enabled is true, we use new config
audio_policy_configuration_bluetooth_hal_enabled.xml

Remove primary flags from hearing aid also.

Bug: 124278829
Bug: 124014853
Test: manual with BluetoothAudioHAL enabled / disabled under Pixel 2, 3
Change-Id: I77e53ee50165e420d28c8a0c8fa9c5fc866c4596