> GitLab Runners do not offer secure isolation between projects that they do builds for. You are TRUSTING all GitLab users who can push code to project A, B or C to run shell scripts on the machine hosting runner X.
Well, there is an issue for that[0]. Also, as of today[1], all shared Runners on GitLab.com are each on their own VM inside Docker containers, so that message does not apply for sure.
Not sure this sounds like the best idea.