[OpenStackAnsible] Transition Train to EM

This transition the train branch to extended maintenance.
Changes for bugfixes and things the team deems important are
still encouraged, but there will no longer be official releases
off of the branch.

Please +1 if the team is ready for us to proceed with this
transition, or -1 if there are any final backports currently in
flight that we should wait for. For the latter case, please
update the patch with the new commit hash after doing a final
release to get those changes out so we know to proceed with the
transition.

Change-Id: I3e1f927cb9ab5152e6e080c2713f1321f52b123f

deliverables/train/openstack-ansible.yaml

@@ -109,6 +109,10 @@ releases:
       - hash: 211e8ce69286ebd4ba5bc0bae2353498dee0012d
         repo: openstack/openstack-ansible
     version: 20.2.6
+  - version: train-em
+    projects:
+      - repo: openstack/openstack-ansible
+        hash: 211e8ce69286ebd4ba5bc0bae2353498dee0012d
 branches:
   - name: stable/train
     location: 20.0.0.0rc1