FIX: Error message when setting enforce 2fa with social logins (PR #10479)

Right now, 2fa does not work with social logins. This PR does not allow sites to set enforce_second_factor for all users if social logins are enabled. This is still allow enforce_second_factor for staff, as staff can just be forced to not use social login.

GitHub

This is a nice way to fix it. I like it!