Include the EE set on a workflow template in the resolver hierarchy

This step comes immediately after checking the actual job/template for
an explicitly set EE.

Note that now, because of how jobs are spawned off of workflow nodes,
the call to .resolve_execution_environment() no longer happens in
.create_unified_job().  The job instance within .create_unified_job()
doesn't yet have access to the node that it will be attached to,
making it impossible to use this information in the resolver if called
there.

awx/main/tasks.py

@@ -3059,8 +3059,8 @@ class AWXReceptorJob:
 
     @property
     def pod_definition(self):
-        if self.task:
-            ee = self.task.instance.resolve_execution_environment()
+        if self.task and self.task.instance.execution_environment:
+            ee = self.task.instance.execution_environment
         else:
             ee = get_default_execution_environment()