CI: Configure ephemeral disk using Kolla role

Depends-On: https://review.opendev.org/c/openstack/kolla/+/899465
Change-Id: I876536263865077b7ecb2288ad95061292babcce

tests/pre.yml

@@ -4,6 +4,7 @@
   vars:
     logs_dir: "/tmp/logs"
   roles:
+    - configure-ephemeral
     - multi-node-firewall
     - role: multi-node-vxlan-overlay
       vars: