[fix] Remove URL creation form from 404

[zamentur]

The problem

With ldap config activated, the url creation form is available if we are going onto non existing link.

The solution

Here i simply hide this form by creating a 404 page in templates...
A better solution could exist.

Todo:

• I didn't check if API is available too
• I don't know how work the i18n tool chain of lstu, so i have not added the i18n key