Should installing Runner to a cluster disable shared runners?
Description
We let you install the GitLab Runner to a Kubernetes cluster, which sets it up as a project-specific runner, but we leave shared runners enabled, so it's random which runner actually gets used. First off, this is confusing for people and unexpected. But without changing the way project runners work in general, we could at least consider automatically disabling shared runners for the project once we set up the specific runner.