Add victoria/wallaby/xena stable branch jobs on master gate

We have stable/victoria, stable/wallaby, and
stable/xena released so we should add their job on
master gate to keep branchless tempest plugins compatible
to those branch.

This also removes the stable/train|stein|rocky job as they
are in EM state now.

Ref: Tempest plugins guide for stable branch testing:
- https://docs.openstack.org/tempest/latest/stable_branch_testing_policy.html

Change-Id: I1ae7cf05a7e73f2f05eaaa27cd3613beb0c455a9

.zuul.yaml

@@ -1,33 +1,27 @@
-- job:
-    name: zun-tempest-py35-docker-sql-rocky
-    parent: zun-tempest-py35-docker-sql
-    nodeset: openstack-single-node-xenial
-    override-checkout: stable/rocky
-    vars:
-      branch_override: stable/rocky
-
-- job:
-    name: zun-tempest-py35-docker-sql-stein
-    parent: zun-tempest-py35-docker-sql
-    nodeset: openstack-single-node-bionic
-    override-checkout: stable/stein
-    vars:
-      branch_override: stable/stein
-
-- job:
-    name: zun-tempest-py3-docker-sql-train
-    parent: zun-tempest-py3-docker-sql
-    nodeset: openstack-single-node-bionic
-    override-checkout: stable/train
-    vars:
-      branch_override: stable/train
-
 - job:
     name: zun-tempest-py3-docker-sql-ussuri
     parent: zun-tempest-py3-docker-sql
     nodeset: openstack-single-node-bionic
     override-checkout: stable/ussuri
 
+- job:
+    name: zun-tempest-py3-docker-sql-victoria
+    parent: zun-tempest-py3-docker-sql
+    nodeset: openstack-single-node-focal
+    override-checkout: stable/victoria
+
+- job:
+    name: zun-tempest-py3-docker-sql-wallaby
+    parent: zun-tempest-py3-docker-sql
+    nodeset: openstack-single-node-focal
+    override-checkout: stable/wallaby
+
+- job:
+    name: zun-tempest-py3-docker-sql-xena
+    parent: zun-tempest-py3-docker-sql
+    nodeset: openstack-single-node-focal
+    override-checkout: stable/xena
+
 - project:
     templates:
       - check-requirements
@@ -36,16 +30,16 @@
     check:
       jobs:
         - zun-tempest-py3-docker-sql
-        - zun-tempest-py35-docker-sql-rocky
-        - zun-tempest-py35-docker-sql-stein
-        - zun-tempest-py3-docker-sql-train
         - zun-tempest-py3-docker-sql-ussuri
+        - zun-tempest-py3-docker-sql-victoria
+        - zun-tempest-py3-docker-sql-wallaby
+        - zun-tempest-py3-docker-sql-xena
         - zun-tempest-multinode-docker-sql
     gate:
       queue: zun
       jobs:
         - zun-tempest-py3-docker-sql
-        - zun-tempest-py35-docker-sql-rocky
-        - zun-tempest-py35-docker-sql-stein
-        - zun-tempest-py3-docker-sql-train
         - zun-tempest-py3-docker-sql-ussuri
+        - zun-tempest-py3-docker-sql-victoria
+        - zun-tempest-py3-docker-sql-wallaby
+        - zun-tempest-py3-docker-sql-xena