Optimize cross-border bandwidth for gitlab.cn

• registry.gitlab.com test images

ci/frontend.gitlab-ci.yml: image: registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.7.2-git-2.31-lfs-2.9-node-14.15-yarn-1.22-graphicsmagick-1.3.36
ci/frontend.gitlab-ci.yml: image: registry.gitlab.com/gitlab-org/gitlab-build-images:danger
ci/docs.gitlab-ci.yml: image: registry.gitlab.com/gitlab-org/gitlab-docs/lint-markdown:alpine-3.13-vale-2.10.2-markdownlint-0.26.0
ci/docs.gitlab-ci.yml: image: registry.gitlab.com/gitlab-org/gitlab-docs/lint-html:alpine-3.13-ruby-2.7.2-d2b92621
ci/global.gitlab-ci.yml: image: "registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.7.2.patched-golang-1.16-git-2.31-lfs-2.9-chrome-89-node-14.15-yarn-1.22-postgresql-11-graphicsmagick-1.3.36"
ci/global.gitlab-ci.yml: image: "registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.7.2.patched-golang-1.16-git-2.31-lfs-2.9-chrome-89-node-14.15-yarn-1.22-postgresql-12-graphicsmagick-1.3.36"
ci/global.gitlab-ci.yml: image: "registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.7.2.patched-golang-1.16-git-2.31-lfs-2.9-chrome-89-node-14.15-yarn-1.22-postgresql-13-graphicsmagick-1.3.36"
ci/global.gitlab-ci.yml: image: "registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.7.2.patched-golang-1.16-git-2.31-lfs-2.9-chrome-89-node-14.15-yarn-1.22-postgresql-11-graphicsmagick-1.3.36"
ci/global.gitlab-ci.yml: image: "registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.7.2.patched-golang-1.16-git-2.31-lfs-2.9-chrome-89-node-14.15-yarn-1.22-postgresql-12-graphicsmagick-1.3.36"
ci/global.gitlab-ci.yml: image: "registry.gitlab.com/gitlab-org/gitlab-build-images:ruby-2.7.2.patched-golang-1.16-git-2.31-lfs-2.9-chrome-89-node-14.15-yarn-1.22-postgresql-13-graphicsmagick-1.3.36"
ci/global.gitlab-ci.yml:  name: registry.gitlab.com/gitlab-org/gitlab-build-images:kaniko
ci/workhorse.gitlab-ci.yml:  - name: registry.gitlab.com/gitlab-org/build/cng/gitaly:latest
ci/dast.gitlab-ci.yml:  name: "registry.gitlab.com/gitlab-org/security-products/dast:$DAST_VERSION"
ci/reports.gitlab-ci.yml:  name: registry.gitlab.com/gitlab-com/gl-security/security-research/package-hunter-cli:1.1.0
ci/review.gitlab-ci.yml: image: registry.gitlab.com/gitlab-org/gitlab-build-images:gitlab-helm3-kubectl1.14
ci/review.gitlab-ci.yml: image: registry.gitlab.com/gitlab-org/gitlab-build-images:gitlab-helm3.5-kubectl1.17

there might be more

• Confirm gitaly-ruby-gems-v1 gitaly-binaries go-pkg-v1 caches are working.

• bin/rake gitlab:assets:compile invokes yarn install, could be switched to internal source.