MOB-38451: Add LoopController requested testname attribute when modifying thread group (#1908)

Author: henrychv

bzt/jmx/base.py

@@ -627,7 +627,8 @@ def get_thread_group(concurrency=None, rampup=0, hold=0, iterations=None,
                              name="ThreadGroup.main_controller",
                              elementType="LoopController",
                              guiclass="LoopControlPanel",
-                             testclass="LoopController")
+                             testclass="LoopController",
+                             testname="Loop Controller")
 
         # 'true' causes endless execution of TG in non-gui mode
         loop.append(JMX._bool_prop("LoopController.continue_forever", False))