Set airship-citycloud mirror url to opendev.org
Set airship-citycloud mirror url to opendev.org

New clouds aren't getting openstack.org mirrors but instead opendev.org
names. We have to override the mirror name based on region and cloud in
order for jobs to properly find the mirror.

Change-Id: I4ed2f55416f1898746c414b2c443bc9bd5a100fe

openstack-infra/project-config,openstack-infra/project-config