Build: remove ancient checks/check-ra.py
The functionality is covered by test_cert_plugin.py and the unused
checks directory was just polluting the tarball (and never executed).
https://fedorahosted.org/freeipa/ticket/6418
Reviewed-By: Martin Basti <mbasti@redhat.com>
Reviewed-By: Christian Heimes <cheimes@redhat.com>