CNG pipeline pushes all images to two registries
We needed to push images to both gcr and GitLab registry as part of gitlab-org/build/CNG!93 (merged) . While reviewing https://gitlab.com/gitlab-org/build/CNG/blob/master/.gitlab-ci.yml and https://gitlab.com/gitlab-org/build/CNG/blob/master/build-scripts/build.sh#L40-43 I've noticed that we push to both registry at every build. This is not really needed and we should try to optimise this.
Images should be mirrored to gcr only for tagged versions. I am also unsure why we need to tag and push 2 times as per https://gitlab.com/gitlab-org/build/CNG/blob/master/build-scripts/build.sh#L40-43 , this seems like a bug @twk3 ?