Remove EM stable/xena job from master gate

stable/xena is in EM state. As Tempest and
plugins masters does not support EM stable branches
QA team will be pinning tempest in devstack stable/xena
soon. With that we do not need to test the stable/xena
jobs on master gate

- https://review.opendev.org/c/openstack/releases/+/881254

Change-Id: I94f8511ab4adab2dfba21260c69c6e691911e16d
diff --git a/.zuul.yaml b/.zuul.yaml
index 7bdfc0e..87612e8 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -16,12 +16,6 @@
     nodeset: openstack-single-node-focal
     override-checkout: stable/yoga
 
-- job:
-    name: designate-bind9-stable-xena
-    parent: designate-bind9
-    nodeset: openstack-single-node-focal
-    override-checkout: stable/xena
-
 - project:
     templates:
       - designate-devstack-jobs
@@ -34,5 +28,4 @@
         - designate-bind9-stable-antelope
         - designate-bind9-stable-zed
         - designate-bind9-stable-yoga
-        - designate-bind9-stable-xena
         - neutron-tempest-plugin-designate-scenario