Instantiate pref controllers from xml if it's defined.

- If a <preference> tag also defines a controller, we will try to
  instantiate it before displaying the UI. The same logic is shared by
  BaseSearchIndexProvider so it also drives search suppression.

- If user also defines a list of controllers programatically, the
  programatically created ones takes precedence.

Bug: 73668763
Test: WIP
Change-Id: I7aecec270bcd3af261e012ef1f6995d2a523cfa1

src/com/android/settings/connecteddevice/ConnectedDeviceDashboardFragment.java

@@ -119,15 +119,7 @@ public class ConnectedDeviceDashboardFragment extends DashboardFragment {
 
                 @Override
                 public List<String> getNonIndexableKeys(Context context) {
-
                     return new ArrayList<>();
                 }
-
-                @Override
-                public List<AbstractPreferenceController> getPreferenceControllers(
-                        Context context) {
-                    //TODO(b/69333961): update the index for controllers
-                    return super.getPreferenceControllers(context);
-                }
             };
 }