Internal projects have limited shared runner time

Summary

It seems both Private and Internal projects have limited shared runner time, but this is not properly documented. The closest I could find is https://about.gitlab.com/gitlab-com/, where it says:

Do limits apply to public and private projects?

The minutes limit only applies to private projects.

It doesn't mention Internal projects, but the words "only applies to private projecs" are misleading, since the limit applies to internal projects too.

Either the current behaviour should be documented (and the FAQ ammended) or the code should be changed so that internal projects have unlimited runner time as public projects do.

(Note: This replaces #3324 (closed), because I got it wrong, and I only got an error message when I tried to modify it.)

Output of checks

This bug happens on GitLab.com