Privileged mode for the Runner does not actually work

When we brought the runner chart in-tree, we seem to have deleted the privileged mode settings.

For example, if you search in the deployment YML there is no reference to privileged. If you search in the upstream chart, you find multiple results: https://gitlab.com/charts/charts.gitlab.io/blob/master/charts/gitlab-runner/templates/deployment.yaml

We are not setting KUBERNETES_PRIVILEGED or mounting /var/run/docker.sock.