Transition xena-eom branches to EOL

These projects did not even merge the bot-generated updates
to the .gitreview file for the unmaintained/zed branch, so obviously
nobody is caring for them and they should transition to EOL now that
the next branch (2023.1) has reached the end of maintainance.

Since EOL of unmaintained/zed means that all older branches need to be
eoled, too, this patch deals with xena first.

Change-Id: I42583e1b37f1cdc451e1bbdd0df115d6ca679542

deliverables/xena/puppet-designate.yaml

@@ -38,6 +38,10 @@ releases:
     projects:
       - repo: openstack/puppet-designate
         hash: 734e498ac69fb0ef8d7cd4e66f66102aae655d08
+  - version: xena-eol
+    projects:
+      - repo: openstack/puppet-designate
+        hash: 734e498ac69fb0ef8d7cd4e66f66102aae655d08
 branches:
   - name: stable/xena
     location: 19.4.0