[Output Switcher] Follow up change of output switcher for mertial next

1. move disconnected status to subtitle.
2. clean up onBind method.
check bug for before/after screenshot.

Bug: 191890668
Test: atest MediaOutputAdapterTest MediaOutputControllerTest MediaOutputBaseDialogTest MediaOutputDialogTest MediaOutputGroupAdapterTest MediaOutputGroupDialogTest
Change-Id: Icbb714e03376632a8934a08cefc4ffee27b19138