Use ubi 8 as base image for ironic

This should install correct base python3 packages.
We might need to combine this with openshift#4836 to have the correct
ironic packages installed.

ci-operator/config/openshift/ironic-image/openshift-ironic-image-release-4.3.yaml

@@ -1,8 +1,8 @@
 base_images:
-  base:
-    name: "4.3"
+  os:
+    name: ubi
     namespace: ocp
-    tag: base
+    tag: "8"
 build_root:
   image_stream_tag:
     cluster: https://api.ci.openshift.org
@@ -20,8 +20,10 @@ promotion:
 raw_steps:
 - pipeline_image_cache_step:
     commands: |
-      curl http://base-openstack-4-2.ocp.svc > /etc/yum.repos.d/base-openstack-4-2.repo
-    from: base
+      rm -rf /etc/yum.repos.d/*
+      curl http://base-4-3-rhel8.ocp.svc > /etc/yum.repos.d/base-4-3-rhel8.repo
+      curl http://openstack-beta-4-3.ocp.svc > /etc/yum.repos.d/openstack-beta-4-3.repo
+    from: os
     to: base-os
 resources:
   '*':