Updating Dockerfile baseimages to mach ocp-build-data config

This PR is autogenerated by the [ocp-build-data-enforcer][1].
It updates the baseimages in the Dockerfile used for promotion in order to ensure it
matches the configuration in the [ocp-build-data repository][2] used
for producing release artifacts.

If you believe the content of this PR is incorrect, please contact the dptp team in
#forum-testplatform.

[1]: https://github.com/openshift/ci-tools/tree/master/cmd/ocp-build-data-enforcer
[2]: https://github.com/openshift/ocp-build-data/tree/openshift-4.6-rhel-8/images

Author: openshift-bot

Dockerfile

@@ -1,4 +1,4 @@
-FROM openshift/origin-release:golang-1.14 as builder
+FROM registry.svc.ci.openshift.org/ocp/builder:rhel-8-golang-openshift-4.6 as builder
 
 RUN yum update -y && \
     yum install -y sqlite && \
@@ -18,7 +18,7 @@ RUN make build
 # 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 openshift/origin-base
+FROM registry.svc.ci.openshift.org/ocp/4.6:base
 
 RUN mkdir /registry
 WORKDIR /registry