Update stale Javadoc in MetaDataMappingService#executeRefresh

This commit updates a stale Javadoc on
MetaDataMappingService#executeRefresh. Previously this method handled
refresh and update tasks. Update tasks have been removed and the method
was renamed, but the Javadoc was not updated to reflect this.

core/src/main/java/org/elasticsearch/cluster/metadata/MetaDataMappingService.java

@@ -85,7 +85,7 @@ public class MetaDataMappingService extends AbstractComponent {
     }
 
     /**
-     * Batch method to apply all the queued refresh or update operations. The idea is to try and batch as much
+     * Batch method to apply all the queued refresh operations. The idea is to try and batch as much
      * as possible so we won't create the same index all the time for example for the updates on the same mapping
      * and generate a single cluster change event out of all of those.
      */