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/notification/ConfigureNotificationSettings.java

@@ -218,9 +218,6 @@ public class ConfigureNotificationSettings extends DashboardFragment implements
                 public List<String> getNonIndexableKeys(Context context) {
                     final List<String> keys = super.getNonIndexableKeys(context);
                     keys.add(KEY_SWIPE_DOWN);
-                    keys.add(KEY_LOCKSCREEN);
-                    keys.add(KEY_LOCKSCREEN_WORK_PROFILE);
-                    keys.add(KEY_LOCKSCREEN_WORK_PROFILE_HEADER);
                     return keys;
                 }
             };