Add Tempest gate job for stable/ussuri

Now we have stable/ussuri branch ready for devstack
and so does for all service projects.

This commit adds the Tempest testing for stable/ussuri
by adding new jobs running on stable/ussuri version of
openstack.

Depends-On: https://review.opendev.org/#/c/723605/

Change-Id: Ifa7887675d34ab8169347b69a8e1ff723b55e466

.zuul.yaml

@@ -446,6 +446,11 @@
         devstack_localrc:
           USE_PYTHON3: true
 
+- job:
+    name: tempest-full-ussuri-py3
+    parent: tempest-full-py3
+    override-checkout: stable/ussuri
+
 - job:
     name: tempest-full-train-py3
     parent: tempest-full-py3
@@ -644,6 +649,8 @@
         - tempest-full-py3-ipv6:
             voting: false
             irrelevant-files: *tempest-irrelevant-files
+        - tempest-full-ussuri-py3:
+            irrelevant-files: *tempest-irrelevant-files
         - tempest-full-train-py3:
             irrelevant-files: *tempest-irrelevant-files
         - tempest-full-stein-py3:
@@ -736,6 +743,7 @@
             irrelevant-files: *tempest-irrelevant-files
     periodic-stable:
       jobs:
+        - tempest-full-ussuri-py3
         - tempest-full-train-py3
         - tempest-full-stein-py3
         - tempest-full-rocky-py3