cleanup cert-manager installation for kops-registry

Currently we install cert-manager manually with helm install.

As magnum includes an automatic release of this component with the label --labels cert_manager_io_enabled=true we can add this to the deployment labels.

• Drop the ClusterIssuer install from the templates
• Create a job to overwrite the ClusterIssuer definitions as appropriate
• Change the ingress annotations to select the correct ClusterIssuer as appropriate