Fix group cast volume slider not disabled after switching to group

devices.

Test: manual build and verify

Bug: 222443976
Change-Id: Ie9f126bb2f4cbc3c6148f41092ada4bfdfa29f99

src/com/android/settings/notification/RemoteVolumeGroupController.java

@@ -119,6 +119,7 @@ public class RemoteVolumeGroupController extends BasePreferenceController implem
                 if (seekBarPreference.getProgress() != info.getVolume()) {
                     seekBarPreference.setProgress(info.getVolume());
                 }
+                seekBarPreference.setEnabled(mLocalMediaManager.shouldEnableVolumeSeekBar(info));
             } else {
                 // Add slider
                 seekBarPreference = new RemoteVolumeSeekBarPreference(mContext);