Updating ose-installer builder & base images to be consistent with ART

Reconciling with https://github.com/openshift/ocp-build-data/tree/4a98c8d67fb1b0233d689c4bcc7f97e61da53999/images/ose-installer.yml

images/installer/Dockerfile.ci

@@ -1,13 +1,13 @@
 # This Dockerfile is used by CI to publish the installer image.
 # It builds an image containing only the openshift-install.
 
-FROM registry.svc.ci.openshift.org/ocp/builder:rhel-8-golang-1.15-openshift-4.6 AS builder
+FROM registry.ci.openshift.org/ocp/builder:rhel-8-golang-1.15-openshift-4.6 AS builder
 WORKDIR /go/src/github.com/openshift/installer
 COPY . .
 RUN hack/build.sh
 
 
-FROM registry.svc.ci.openshift.org/ocp/4.6:base
+FROM registry.ci.openshift.org/ocp/4.6:base
 COPY --from=builder /go/src/github.com/openshift/installer/bin/openshift-install /bin/openshift-install
 RUN mkdir /output && chown 1000:1000 /output
 USER 1000:1000