Hide pull mirroring update time from project visitors

Problem

When a project has "Repository mirroring" with the Pull direction enabled, visitors with the Maintainer level can see both the original location of the project, as well as when it last got updated. Visitors with a permission level below Maintainer will not be able to see the original location, but still can see the last time it got updated.

Maintainer	Guest

We should display both information only visitors with the Maintainer level, as they are the one responsible for it and with the power to change things if something is going wrong.