ipa-advise: remove plugin config-fedora-authconfig
ipa-advise config-fedora-authconfig produces a script with authconfig
instructions for configuring Fedora 18/19 client with IPA server
without use of SSSD. Fedora 18 and 19 are not supported any more,
so the plugin could be removed.
Resolves: https://pagure.io/freeipa/issue/7533
Reviewed-By: Petr Vobornik <pvoborni@redhat.com>