Improve UI for CI_JOB_TOKEN allowlist

Follow-up from this discussion:

If somebody removes their own project from the limit section, will the token still work for pushing? Maybe the name of the repo should include (default) comment with popup that says "own repository can not be removed from CI_JOB_TOKEN access scope". Maybe the box should not be shown at all until some "Enable access to this project from other projects" is checked.

By default, we include the project to its own allowlist. The user cannot remove their own project from the allowlist, but this is not made clear in the UI unless other projects are included in the list (for comparison, since the delete icon is not present for the project).

For reference, this is how the Token Access section looks like right now: