Removed useless and illegal json object in the response.

Relates to #5865

src/main/java/org/elasticsearch/action/search/ClearScrollResponse.java

@@ -69,8 +69,6 @@ public class ClearScrollResponse extends ActionResponse implements StatusToXCont
 
     @Override
     public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
-        builder.startObject();
-        builder.endObject();
         return builder;
     }