Suppress work-profile search terms when no AfW is on device

- Share the same set of pref controller between main UI and search
  in AccountDashboardFragment.
- Update WorkSoundPreferenceController to actually do something for
  updateNonIndexable() method.
- LockscreenDashboardFragment to also suppress "Work notification" header. I
  think we just missed it previously.

Change-Id: Ifa6f9b2077c9810ffff33f240929f418d4a8a5aa
Fixes: 62167659
Test: robotests

src/com/android/settings/security/LockscreenDashboardFragment.java

@@ -159,6 +159,7 @@ public class LockscreenDashboardFragment extends DashboardFragment
                     final List<String> niks = super.getNonIndexableKeys(context);
                     niks.add(KEY_ADD_USER_FROM_LOCK_SCREEN);
                     niks.add(KEY_LOCK_SCREEN_NOTIFICATON_WORK_PROFILE);
+                    niks.add(KEY_LOCK_SCREEN_NOTIFICATON_WORK_PROFILE_HEADER);
                     return niks;
                 }
             };