Mirror c9s/rhel-9.6 CoreOS base images (openshift#59544)

These images are built as part of the CoreOS pipeline. They will be used
as bases for building the node images containing OCP-versioned content
for CI.

Part of openshift/enhancements#1637.

core-services/image-mirroring/_config.yaml

@@ -669,6 +669,10 @@ supplementalCIImages:
     image: quay.io/stackrox-io/apollo-ci:stackrox-ui-test-0.4.3
   stackrox/apollo-ci:stackrox-ui-test-0.4.4:
     image: quay.io/stackrox-io/apollo-ci:stackrox-ui-test-0.4.4
+  coreos/scos-base:9:
+    image: quay.io/openshift-release-dev/ocp-v4.0-art-dev:c9s-coreos
+  coreos/rhel-coreos-base:9.6:
+    image: quay.io/openshift-release-dev/ocp-v4.0-art-dev:rhel-9.6-coreos
   coreos/coreos-assembler:latest:
     image: quay.io/coreos-assembler/coreos-assembler:latest
   coreos/coreos-assembler:4.18: