Removed power policy from audio control service.

Removed power policy from audio service as the power policy in emulator
is applied by the car audio service. It uses audio control HAL AIDL to
mute/unmute devices on power policy audio disable/enable.

Bug: 193074739
Test: play emergency audio and verify it remains enabled during power
policy audio disabled.
Test: play media audio and verify it is disabled during power policy
audio disabled.

Change-Id: I6716732f73cb5a6c727eed03de6ac7a347b58213
Merged-In: I6716732f73cb5a6c727eed03de6ac7a347b58213
(cherry picked from commit 37b3d6dd1bc85a16c87eb47037127fb343d5733d)