Re-add undercloud-aodh.yaml

https://review.opendev.org/#/c/611188/ incorrectly removed the
undercloud-aodh.yaml environment file as we still reference it in
python-tripleoclient.

Change-Id: I458dd389ef8a953d5ec8f2bcb0fa454fe0ffffcb
Closes-Bug: #1828893

environments/services/undercloud-aodh.yaml

@@ -0,0 +1,7 @@
+# DEPRECATED. This file will be removed in the Train release as it is no longer
+# needed
+resource_registry:
+  OS::TripleO::Services::AodhApi: ../../deployment/aodh/aodh-api-container-puppet.yaml
+  OS::TripleO::Services::AodhEvaluator: ../../deployment/aodh/aodh-evaluator-container-puppet.yaml
+  OS::TripleO::Services::AodhNotifier: ../../deployment/aodh/aodh-notifier-container-puppet.yaml
+  OS::TripleO::Services::AodhListener: ../../deployment/aodh/aodh-listener-container-puppet.yaml