Allow / grant access to related project container registry
Runner + container registry is super when building an image and pushing the result onto the registry but when coming to pull an image in order to build inside that image because the build requires some dependencies there is actually nothing.
From the documentation, one have to create a fake user and use its login / password and use it to log the user running the runner on the docker registry. That's quite insane to do when you have a tons of projects.
From that task, we already have access to the project files, why not this project container registry?
also see https://gitlab.com/gitlab-org/gitlab-ce/issues/19219