To support cold migration on new Fedora Cloud, I need to have ssh keys for nova and it would be nice to have those keys persistent across reprovision.

Can you please generate using ssh-keygen some key pair and put private key as file in:
{{ private }}/files/openstack/fed-cloud09-nova.key

Mind that there already exist fed-cloud09.key, but that have different usage.

And then please put content of public key as variable in public ansible.git in vars/fedora-cloud.yml
E.g. as variable fed_cloud09_nova_public_key

Once done I will add it to fed-clou09 playbook and deploy.