Update download confirmation warning to be far less LSU-specific AND to remove
a strange dependency on the LSU gradebook.

Solves the following warning:

Invalid get_string() identifier: 'ferpa_required' or component 'grades'. Perhaps you are missing $string['ferpa_required'] = ''; in lang/en/grades.php?

    line 293 of /lib/classes/string_manager_standard.php: call to debugging()
    line 6901 of /lib/moodlelib.php: call to core_string_manager_standard->get_string()
    line 187 of /blocks/ues_people/lib.php: call to get_string()
    line 241 of /blocks/ues_people/lib.php: call to ues_people::ferpa_control()
    line 480 of /blocks/ues_people/index.php: call to ues_people::controls()