Use the correct stream for playback.

We were using the STREAM_MUSIC and playing the using setMode to use the
IN_CALL mode.

Instead, use the STREAM_VOICE_CALL: this works basically the same way,
but does not cause issues when the stream is stopped.

Bug: 5240848
Change-Id: I60595b4da7abe01adb1908ee24a4ca9801a1fa85