Updating operator-registry-container image to be consistent with ART for 4.21

Reconciling with https://github.com/openshift/ocp-build-data/tree/1097a63a576d216981abbff7a60c4c5da67d1644/images/operator-registry.yml

Author: AOS Automation Release Team

operator-registry.Dockerfile

@@ -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
 
 ENV GOPATH /go
 ENV PATH $GOPATH/bin:/usr/local/go/bin:$PATH
@@ -11,7 +11,7 @@ RUN make build/registry cross
 # copy and build vendored grpc_health_probe
 RUN CGO_ENABLED=0 go build -mod=vendor -tags netgo -ldflags "-w" ./vendor/github.com/grpc-ecosystem/grpc-health-probe/...
 
-FROM registry.ci.openshift.org/ocp/4.20:base-rhel9
+FROM registry.ci.openshift.org/ocp/4.21:base-rhel9
 
 COPY --from=builder /src/bin/* /bin/registry/
 COPY --from=builder /src/grpc-health-probe /bin/grpc_health_probe