OboeTester can use setPreferredMixerAttributes() to reduce USB latency

The latency tests can use [AudioManager.setPreferredMixerAttributes()](https://developer.android.com/reference/android/media/AudioManager#setPreferredMixerAttributes(android.media.AudioAttributes,%20android.media.AudioDeviceInfo,%20android.media.AudioMixerAttributes)) to make the USB formats match the app attributes more closely.
This can prevent extra processing and reduce latency. [[internal discussion]](https://b.corp.google.com/issues/364387399)

The preference should be cleared when the test is finished.

The supported attributes can be listed in the DeviceReport.

If this works well then we can move it into CTS Verifier.