UPSTREAM: <carry>: Updating ose-cluster-kube-cluster-api-operator-container image to be consistent with ART for 4.21

Reconciling with https://github.com/openshift/ocp-build-data/tree/cda27b92c8f2167e8bcadfb2337bc4d93b39e032/images/ose-cluster-kube-cluster-api-operator.yml

Author: AOS Automation Release Team

.ci-operator.yaml

@@ -1,4 +1,4 @@
 build_root_image:
   name: release
   namespace: openshift
-  tag: rhel-9-release-golang-1.24-openshift-4.20
+  tag: rhel-9-release-golang-1.24-openshift-4.21

openshift/Dockerfile.openshift

@@ -1,4 +1,4 @@
-FROM registry.ci.openshift.org/ocp/builder:rhel-9-golang-1.24-openshift-4.20 AS builder
+FROM registry.ci.openshift.org/ocp/builder:rhel-9-golang-1.24-openshift-4.21 AS builder
 
 WORKDIR /build
 COPY . .
@@ -7,7 +7,7 @@ RUN GO111MODULE=on CGO_ENABLED=0 GOOS=${GOOS} GOPROXY=${GOPROXY} go build \
   -o=cluster-api-operator \
   cmd/main.go
 
-FROM registry.ci.openshift.org/ocp/4.20:base-rhel9
+FROM registry.ci.openshift.org/ocp/4.21:base-rhel9
 
 LABEL description="Cluster API Operator"