frontend: revert wrong optimization in createrepo
    
    CoprChrootsLogic.new_from_names() mistakenly filtered the createrepo
    action by "chroots" using "dirnames" logic.  So the code then naturally
    claimed something like "there's no such CoprDir=fedora-rawhide-x86_64".
    We indeed want to filter by chroot on that place, but it will be done
    later.
    
    So drop the unused main_only argument from send_createrepo(), and
    uncomment 'raise exceptions.NotFoundException' - it should help us
    diagnose mistakenly called send_createrepo() in future.
    
    Merges: #1146