correctly inherit extra_vars

* inherit extra_vars from job_template
* overwrite with extra vars survey default vars
* overwrite with job extra_vars
* bypass extra_vars inherit logic for job relaunch
* with tests

awx/api/views.py

@@ -2207,6 +2207,7 @@ class JobRelaunch(RetrieveAPIView, GenericAPIView):
         if not serializer.is_valid():
             return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
 
+        obj.launch_type = 'relaunch'
         new_job = obj.copy()
         result = new_job.signal_start(**request.DATA)
         if not result: