[web] everything old is new again
Kill the "new" cubicweb.css, and move cubicweb.old.css back in its
place. Closes #4763360.
option_group_changed('port', 'main', 'web')
option_group_changed('query-log-file', 'main', 'web')
option_group_changed('profile', 'main', 'web')
option_group_changed('max-post-length', 'main', 'web')