Only set fullIndex flag when performing a full update

Previously UpdateData#fullIndex was default true which meant if a
partial update came in before a call to Index#update() then the
partial update would be treated as a full index and future calls
to Index#update() would be ignored.

Bug: 30366360
Change-Id: I6e2738c25c9623f49171ecba0f3e0ce0076b7e42

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

@@ -177,8 +177,8 @@ public class Index {
         public List<SearchIndexableData> dataToDelete;
         public Map<String, List<String>> nonIndexableKeys;
 
-        public boolean forceUpdate = false;
-        public boolean fullIndex = true;
+        public boolean forceUpdate;
+        public boolean fullIndex;
 
         public UpdateData() {
             dataToUpdate = new ArrayList<SearchIndexableData>();