With the new [DockerHub
limits](https://docs.docker.com/docker-hub/download-rate-limit/) users
are reaching limits because they are pulling
`gitlab/gitlab-runner-helper` image from DockerHub registry.

Start publishing the helper image to the GitLab.com registry to provide
an alternative hosting of the helper image.

Phase 1 of https://gitlab.com/gitlab-org/gitlab-runner/-/issues/27196#phase-1

reference https://gitlab.com/gitlab-org/gitlab-runner/-/issues/27196