Fix issue where disconnect tone is truncated on call disconnect.

The tone generator path waits until the tone is done playing before
signaling to CallAudioManager that the tone has completed.  The media
path was not waiting for tone playback to complete before signaling
CallAudioManager.  As a result, CallAudioManager would release audio
focus before the tone stopped playing, sometimes resulting in it being
cut off or playing over the wrong audio route.

Test: Manual.
Bug: 111313134
Change-Id: I8f1a098f89b7e2db09bb719c04991804c3e92fbc