Continue playing audio if output to local device is selected by the user

Audio will continue playing if the user explicitly selected the
local device as output.
However, if the local device was selected implicitly because the
remote device has been disconnected, then the music will stop
before selecting the local device as output.

Bug: 77192195
Test: Manual - play music to Bluetooth Headset, then either
      (a) Select local device as output; (b) disconnect Headset
Change-Id: I9253b7983ac40951f17876db44919830984201d3