Add android.virtualdevice.cts.VirtualAudioTest to postsubmit

These tests exercise audio playback and capture on CF and are
useful in spotting issues in the audio pipeline end-to-end.

Bug: 316017930
Test: atest CtsVirtualDevicesTestCases
Change-Id: If625cec5bc2d281f1e0d99b820f604f1bac7b621