[nova] Transition Xena to EM

This transition the stable/xena 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 after the transition.

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.

The transition deadline is April 20th, 2023.

Change-Id: I25980e149389fd7650d77dcda835007a387d29c6

deliverables/xena/nova.yaml

@@ -57,6 +57,10 @@ releases:
     projects:
       - repo: openstack/nova
         hash: 706ee6010a3720b9d9faf72d6782665b6eb083a7
+  - version: xena-em
+    projects:
+      - repo: openstack/nova
+        hash: 706ee6010a3720b9d9faf72d6782665b6eb083a7
 branches:
   - name: stable/xena
     location: 24.0.0.0rc1

deliverables/xena/os-vif.yaml

@@ -20,6 +20,10 @@ releases:
     projects:
       - repo: openstack/os-vif
         hash: 8d14a1c6a9eeaef0fdae9ea1210d3310a3498d78
+  - version: xena-em
+    projects:
+      - repo: openstack/os-vif
+        hash: 8d14a1c6a9eeaef0fdae9ea1210d3310a3498d78
 branches:
   - name: stable/xena
     location: 2.6.0

deliverables/xena/osc-placement.yaml

@@ -23,6 +23,10 @@ releases:
     projects:
       - repo: openstack/osc-placement
         hash: 0ea8f1b05d4aa4a6f144adff08771f5b84bda479
+  - version: xena-em
+    projects:
+      - repo: openstack/osc-placement
+        hash: 0ea8f1b05d4aa4a6f144adff08771f5b84bda479
 branches:
   - name: stable/xena
     location: 3.1.1

deliverables/xena/placement.yaml

@@ -21,6 +21,10 @@ releases:
       - repo: openstack/placement
         hash: 1cf167fbadb058f5f8a07022bf4a53473b019221
     diff-start: 5.0.0
+  - version: xena-em
+    projects:
+      - repo: openstack/placement
+        hash: 1cf167fbadb058f5f8a07022bf4a53473b019221
 branches:
   - name: stable/xena
     location: 6.0.0.0rc1

deliverables/xena/python-novaclient.yaml

@@ -15,6 +15,10 @@ releases:
     projects:
       - repo: openstack/python-novaclient
         hash: 8066f8c745054caeb7bd66d4c2be15ab5fac1d1f
+  - version: xena-em
+    projects:
+      - repo: openstack/python-novaclient
+        hash: 8066f8c745054caeb7bd66d4c2be15ab5fac1d1f
 branches:
   - name: stable/xena
     location: 17.6.0