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: Ic52b2a8c7266effd970b5211789fce36aa153eb4