Output Switcher shows "+" button next to some non-expandable device

-Remove + icon if there is not selectable device

Bug: 191682821
Test: atest MediaOutputAdapterTest MediaOutputControllerTest MediaOutputBaseDialogTest MediaOutputDialogTest MediaOutputGroupAdapterTest MediaOutputGroupDialogTest
Change-Id: I89ccadad176e3f9ea0cc8796d4934ddc5a9d5def
2 files changed