Improve example DAG for ML Engine (#7810)

Author: mik-laj

airflow/providers/google/cloud/example_dags/example_mlengine.py

@@ -172,7 +172,7 @@
 
     training >> create_version
     training >> create_version_2
-    create_model >> get_model >> get_model_result
+    create_model >> get_model >> [get_model_result, delete_model]
     create_model >> create_version >> create_version_2 >> set_defaults_version >> list_version
     create_version >> prediction
     create_version_2 >> prediction