Remove Wallpaper duplicate from setting search

Bug: 33701673
Test: make -j40 RunSettingsRoboTests
Change-Id: I520cbc74284d92ab05b733346ee1b3115ddd8e9f

src/com/android/settings/search/BaseSearchIndexProvider.java

@@ -72,7 +72,7 @@ public class BaseSearchIndexProvider implements Indexable.SearchIndexProvider {
             }
             return nonIndexableKeys;
         } else {
-            return EMPTY_LIST;
+            return new ArrayList<>();
         }
     }