AudioService: fix voice volume adjustments

When evaluating the active stream type for volume adjustements,
also consider STREAM_VOICE_CALL activity outside of calls to
handle situations like voicemail playback.
This negates the need for bad workarounds by apps such as
entering call mode for voicemail, or directly changing SCO
volume (by using value of hidden STREAM_BLUETOOTH_SCO).

Bug: 285185485
Test: OboeTester TEST OUTPUT > play VoiceComm > adjust volume
Change-Id: If24fc55ffa3acc43c11d95f6b31258bb4f59a236