gitlab/gitlab-runner docker image should be ARM64 compatible
Description
As far as I saw in the code the gitlab-runner binaries itself are ARM compatible. The Docker images though (https://hub.docker.com/r/gitlab/gitlab-runner/) are based on ubuntu (or alpine) and only x84_64 compatible.
Proposal
Provide an arm64 Docker image that that will have GitLab Runner so that they can start running GitLab Runner manager inside of a Docker container. As pointed out in !725 (comment 226637168) we have a problem with this because we use dumb-init to have gitlab-runner process start on PID 1. There an open issue upstream that we need to investigate, it was also suggested that we might want to migrate to tini which might be a solution.
Links to related issues and merge requests / references
Edited by Brandon Jung