Promote configure-mirror role to base job
By testing with we can
confirm our site-varaibles have been setup properly on ze01.o.o.
# TODO(mordred) When we have site-local variables, these should go there
zuul_traceroute_host: git.openstack.org
zuul_image_manifest: /etc/dib-builddate.txt
+ - role: configure-mirrors
+ mirror_fqdn: "{{ zuul_site_mirror_fqdn }}"
