When only one device is selected in dynamic group, the device should be disabled

-Check if device id is in selected group rather than comparing client package name
-Add test cases

Bug: 154916764
Test: make -j50 RunSettingsRoboTests
Change-Id: I7364a9e3d807bbfc6b26b8212ab2da67ea329582

src/com/android/settings/media/MediaOutputGroupSlice.java

@@ -238,7 +238,7 @@ public class MediaOutputGroupSlice implements CustomSliceable {
                             + ") is unavailable");
                     return;
                 }
-                if (TextUtils.equals(device.getClientPackageName(), getWorker().getPackageName())) {
+                if (getWorker().isSelectedMediaDevice(device)) {
                     getWorker().removeDeviceFromPlayMedia(device);
                 } else {
                     getWorker().addDeviceToPlayMedia(device);