on host callback, upate dynamic inv only once

* During a job template launch via the host callback launch feature,
when the host launching the job template is not found; we try to launch
associated dyn inv updates to pick up the host. Then the inv is searched
again for the host. If the host is found, then the jt is launched. This
fix carries forward the feature that prevents the dyn inv update with
cache timeout of 0 from being re-launched with the new task manager.

awx/main/scheduler/__init__.py

@@ -230,7 +230,12 @@ class TaskManager():
                 dependencies.append(project_task)
                 # Inventory created 2 seconds behind job
 
+            inventory_sources_already_updated = task.get_inventory_sources_already_updated()
+
             for inventory_source_task in self.graph.get_inventory_sources(task['inventory_id']):
+                if inventory_source_task['id'] in inventory_sources_already_updated:
+                    print("Inventory already updated")
+                    continue
                 if self.graph.should_update_related_inventory_source(task, inventory_source_task['id']):
                     inventory_task = self.create_inventory_update(task, inventory_source_task)
                     dependencies.append(inventory_task)