Revert interface changes to helpers/Service that we cannot make accor…

…ding to revapi.

Also clean up the FulltextIndexBuilder and IndexUpdateSink APIs such that we avoid nulls.

community/kernel/src/main/java/org/neo4j/helpers/Service.java

@@ -119,7 +119,7 @@ public abstract class Service
      * Enabling this is useful for debugging why services aren't loaded where you would expect them to.
      */
     private static final boolean printServiceLoaderStackTraces =
-            flag( Service.class, "printServiceLoaderStackTraces", true );
+            flag( Service.class, "printServiceLoaderStackTraces", false );
 
     private final Set<String> keys;
 
@@ -196,7 +196,7 @@ public static <T extends Service> T loadSilently( Class<T> type, String key )
      * @return the matching Service implementation
      * @throws NoSuchElementException if no service could be loaded with the given key.
      */
-    public static <T extends Service> T load( Class<T> type, String key ) throws NoSuchElementException
+    public static <T extends Service> T load( Class<T> type, String key )
     {
         T service = loadSilently( type, key );
         if ( service == null )