ACL templates are "ignored" after the first start
Steps to reproduce
With a fresh copy of Opencast, when I change the XML files in `/etc/acl` (including removing/adding some) before ever having started this Opencast instance these changes are correctly reflected in the "Access policies" tab of the admin UI.
However, if I change these files after that I can restart Opencast all I want; the changes won't register. Setting the log level to `DEBUG` reveals that every single one of these XML files is ignored by the `AclScanner` on restarts subsequent to the first start.