clouddns: use fqdn for challenge cleanup
clouddns: use fqdn for challenge cleanup

This is the same as the problem fixed in #750, but for cleanup.

jetstack/cert-manager,jetstack-experimental/cert-manager,cert-manager/cert-manager,jetstack/cert-manager,jetstack-experimental/cert-manager,jetstack-experimental/cert-manager,jetstack/cert-manager,cert-manager/cert-manager,cert-manager/cert-manager