Fix the toggle button flicker problem when display

- Root cause: the side effect of the parallel controller loading.
- Solution: disable the parallel approach and remove the entry point
  of parallel approach in DashboardFragment.

Fixes: 187838753
Test: Robo test for AppInfoDashboardFragment, ConfigureNotificationSettings,
      ConnectedDeviceDashboardFragment, DevelopmentSettingsDashboardFragment,
      NetworkDashboardFragment, DashboardFragment
Change-Id: If3b09c4fd6f33042e0ed38704f08e855ab8f5377

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

@@ -49,11 +49,6 @@ public class ConnectedDeviceDashboardFragment extends DashboardFragment {
         return TAG;
     }
 
-    @Override
-    protected boolean isParalleledControllers() {
-        return true;
-    }
-
     @Override
     public int getHelpResource() {
         return R.string.help_url_connected_devices;