End support for stable/xena

This marks the end of support for stable/xena
which is EM now [1]. This remove the stable/xena
jobs and also adds relesenote to mark the end of
support of Xena.

[1] https://review.opendev.org/c/openstack/releases/+/881254
    https://releases.openstack.org/

Change-Id: I1027823aa378e9c669dca5a1bc49a9ada604a3d7
diff --git a/zuul.d/project.yaml b/zuul.d/project.yaml
index be8442a..125f662 100644
--- a/zuul.d/project.yaml
+++ b/zuul.d/project.yaml
@@ -40,7 +40,7 @@
         # those in respective stable branch gate.
         - tempest-full-2023-1:
             irrelevant-files: *tempest-irrelevant-files
-        - tempest-full-xena:
+        - tempest-full-yoga:
             irrelevant-files: *tempest-irrelevant-files
         - tempest-multinode-full-py3:
             irrelevant-files: *tempest-irrelevant-files
@@ -165,7 +165,6 @@
         - tempest-full-parallel
         - tempest-full-zed-extra-tests
         - tempest-full-yoga-extra-tests
-        - tempest-full-xena-extra-tests
         - tempest-full-enforce-scope-new-defaults-zed
         - neutron-ovs-tempest-dvr-ha-multinode-full:
             irrelevant-files: *tempest-irrelevant-files
@@ -188,15 +187,12 @@
         - tempest-full-2023-1
         - tempest-full-zed
         - tempest-full-yoga
-        - tempest-full-xena
         - tempest-slow-2023-1
         - tempest-slow-zed
         - tempest-slow-yoga
-        - tempest-slow-xena
         - tempest-full-2023-1-extra-tests
         - tempest-full-zed-extra-tests
         - tempest-full-yoga-extra-tests
-        - tempest-full-xena-extra-tests
     periodic:
       jobs:
         - tempest-all