Ignition server rendering fails when image mirrors do not include openshift release mirrors

When creating a hosted cluster on a management cluster that has an imagecontentsourcepolicy that does not include openshift-release-dev or ocp/release images, the control plane operator fails reconciliation with an error:

{"level":"error","ts":"2023-08-22T18:26:07Z","msg":"Reconciler error","controller":"hostedcontrolplane","controllerGroup":"hypershift.openshift.io","controllerKind":"HostedControlPlane","HostedControlPlane":{"name":"jiezhao-test","namespace":"clusters-jiezhao-test"},"namespace":"clusters-jiezhao-test","name":"jiezhao-test","reconcileID":"9b3c101b-b4d2-4d9e-b71c-ede9e0b55374","error":"failed to update control plane: failed to reconcile ignition server: failed to parse private registry hosted control plane image reference \"\": repository name must have at least one component","stacktrace":"sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler\n\t/hypershift/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:326\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).processNextWorkItem\n\t/hypershift/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:273\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Start.func2.2\n\t/hypershift/vendor/sigs.k8s.io/controller-runtime/pkg/internal/controller/controller.go:234"}

4.14

always

1. Create an ImageContentSourcePolicy on a management cluster:

apiVersion: operator.openshift.io/v1alpha1
kind: ImageContentSourcePolicy
metadata:
  name: brew-registry
  resourceVersion: "31794"
  uid: 7231c634-da35-4c56-b2ef-be48c2571a9c
spec:
  repositoryDigestMirrors:
  - mirrors:
    - brew.registry.redhat.io
    source: registry.redhat.io
  - mirrors:
    - brew.registry.redhat.io
    source: registry.stage.redhat.io
  - mirrors:
    - brew.registry.redhat.io
    source: registry-proxy.engineering.redhat.com


2. Install the latest hypershift operator and create a hosted cluster with the latest 4.14 ci build

The hostedcluster never creates machines and never gets to a Complete state

The hostedcluster comes up and gets to a Complete state