Shut down AudioPlayer on exit from "HiFi Ultrasound" tests.

Bug: 334986860
Test: run and pass the HiFi UltraSound Speaker Test. Select USB Audio Peripheral Attributes test.
Test: Plug in a USB audio peripheral. Note that the audio from the HiFi Ultrasound Speaker test
Test: DOES NOT PLAY. Also for HiFi Ultrasound Microphone Test.
Flag: TEST_ONLY

Change-Id: I24665bbb835f24589a61b7baf81cb799fc9d82ec