Start relying on ci base image for CI

follow-up of #5618

images/openshift-base-rhel9.yml

@@ -9,19 +9,7 @@ content:
     ci_alignment:
       streams_prs:
         enabled: false
-      mirror: true
-      # The upstream_image_base serves as a starting point for the upstream_image.
-      # ART will mirror the brew build out to upstream_image_base.
-      # ART does not mirror the upstream_image in this case. A buildconfig,
-      # generated by images:streams is triggered when upstream_image_base is updated.
-      # The output of this buildconfig is upstream_image.
-      # This buildconfig layers on files necessary for the resulting upstream_image CI image
-      # to pull RPM dependencies from the CDN & reposync repositories.
-      upstream_image_base: registry.ci.openshift.org/ocp/builder:rhel-9-base-openshift-{MAJOR}.{MINOR}.art
-      # Note that it must be qualified by {MAJOR}.{MINOR} so that it installs non-CDN
-      # rpms for the appropriate release.
-      transform: rhel-9/base-repos
-      upstream_image: registry.ci.openshift.org/ocp/builder:rhel-9-base-openshift-{MAJOR}.{MINOR}
+      mirror: false
     okd_alignment:
       resolve_as:
         stream: centos_stream9