AudioService: Remove orientation tracking

Orientation is superseded with rotation, which provides
more useful information from the audio system perspective.

The ro.audio.monitorOrientation property doesn't seem to be set
in configuration of any device. The "orientation" property
is not analyzed by any available audio HAL.

Bug: 73168241
Test: make
Change-Id: Ie9dd04ea69976708ec807b64380206a7d0bf4691