[vitrage] Transition Zed to Unmaintained

This branch reached the end of its official stable maintained period,
hence this patch transition stable/zed branch to Unmaintained. (For
details about Unmaintained state please see: [1][2])

The transitions is as follows:
- tip of the stable/zed branch is tagged with zed-eom tag
- unmaintained/zed branch will be cut from zed-eom tag
- stable/zed branch will be deleted

Note:
- there will no longer be official releases off of zed branch after this
  transition
- backports can be pushed to unmaintained/yoga branch
- openstack-unmaintained-core (or <project>-unmaintained-core groups if
  such exists) have the rights to merge patches

Important: please +1 if the team is ready for us to proceed with this
transition, or -1 if there are any final Zed stable release with
backports currently in flight that we should wait for. For the latter
case, please propose a final Zed stable release patch, and rebase this
patch on top of that, with the latest commit hash of stable/zed.

The transition deadline is May 2nd, 2024. [3]

[1] https://docs.openstack.org/project-team-guide/stable-branches.html#unmaintained
[2] https://governance.openstack.org/tc/resolutions/20230724-unmaintained-branches.html
[3] https://releases.openstack.org

Change-Id: I576b84b39af225a7a2c99dc6079911954c2158e6

deliverables/zed/python-vitrageclient.yaml

@@ -11,7 +11,14 @@ releases:
     projects:
       - repo: openstack/python-vitrageclient
         hash: 716be849831d2a12abb7a1e6b6646366acf86859
+  - version: zed-eom
+    projects:
+      - repo: openstack/python-vitrageclient
+        hash: 78fe3af414325e3a66dfe68956483500e6cc8b76
 branches:
   - name: stable/zed
     location: 4.6.0
-release-notes: https://docs.openstack.org/releasenotes/python-vitrageclient/zed.html
+  - name: unmaintained/zed
+    location: zed-eom
+release-notes:
+  https://docs.openstack.org/releasenotes/python-vitrageclient/zed.html

deliverables/zed/vitrage-dashboard.yaml

@@ -10,7 +10,13 @@ releases:
     projects:
       - repo: openstack/vitrage-dashboard
         hash: 3025f2b4f01e86e8585c5a951467d32f347842a0
+  - version: zed-eom
+    projects:
+      - repo: openstack/vitrage-dashboard
+        hash: f8cf5b2e39a31651668e424143988f469df879c6
 branches:
   - name: stable/zed
     location: 3.6.0
+  - name: unmaintained/zed
+    location: zed-eom
 release-notes: https://docs.openstack.org/releasenotes/vitrage-dashboard/zed.html

deliverables/zed/vitrage.yaml

@@ -10,7 +10,13 @@ releases:
     projects:
       - repo: openstack/vitrage
         hash: 9a9710558b34b15eee7f67e94ad04c8fc022d2e8
+  - version: zed-eom
+    projects:
+      - repo: openstack/vitrage
+        hash: 432aec7aa13b43ad34f635e3cc87a3c20011d3f1
 branches:
   - name: stable/zed
     location: 9.0.0
+  - name: unmaintained/zed
+    location: zed-eom
 release-notes: https://docs.openstack.org/releasenotes/vitrage/zed.html