CI: Test ironic on nova-cell change

This fixes CI regression after nova split into main and cell roles.
To follow original testing patterns, let's test ironic also when
nova-cell role changes.

Change-Id: Iaada93fc7b7bf3ed86f9d9198890f199a726b4d8

zuul.d/base.yaml

@@ -66,7 +66,7 @@
     parent: kolla-ansible-base
     voting: false
     files:
-      - ^ansible/roles/(ironic|nova)/
+      - ^ansible/roles/(ironic|nova|nova-cell)/
       - ^tests/test-ironic.sh
       - ^tests/test-dashboard.sh
     vars: