[CI] Run the cells scenario on Ubuntu

With CentOS-based jobs disabled, we don't have any job testing the
cells scenario. This patch adds it for Ubuntu.

Change-Id: Ic872242717006085f4dc586b0aea0e068f064a4b

zuul.d/jobs.yaml

@@ -344,6 +344,13 @@
     vars:
       base_distro: centos
 
+- job:
+    name: kolla-ansible-ubuntu-source-cells
+    parent: kolla-ansible-cells-base
+    nodeset: kolla-ansible-jammy-multi
+    vars:
+      base_distro: ubuntu
+
 - job:
     name: kolla-ansible-centos8s-source-cells
     parent: kolla-ansible-cells-base

zuul.d/project.yaml

@@ -42,6 +42,7 @@
         - kolla-ansible-ubuntu-source-upgrade
         - kolla-ansible-ubuntu-binary-upgrade
         # - kolla-ansible-centos8s-source-cells
+        - kolla-ansible-ubuntu-source-cells
         # - kolla-ansible-centos8s-source-mariadb
         - kolla-ansible-ubuntu-source-mariadb
         # - kolla-ansible-centos8s-source-ovn