Use searchable="false" to suppress nonIndexables.

When possible, remove or simplify getNonIndexable() logic in fragments,
and use searchable="false" in xml to suppress index.

Change-Id: I5bdf5bc7d5494a64cdd9e230a51321a4b210af69
Fixes: 112608186
Test: robotest and manual search

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

@@ -154,8 +154,6 @@ public class LockscreenDashboardFragment extends DashboardFragment
                 public List<String> getNonIndexableKeys(Context context) {
                     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;
                 }