Use upstream gitlab-runner
Currently there is an obstacle in doing this
https://gitlab.com/charts/gitlab-runner/blob/master/templates/_helpers.tpl#L22 helper template expects to have gitlab-runner.gitlabUrl
value passed
This means that in addition to specifying the domain user needs to also specify this url which is probably the same.
We'll need to implement a default which fallbacks to a gitlab.{{.Values.global.hosts.domain}}