fix: set docker_registry_ca to '' if not secure

Set `docker_registry_ca` to empty string if `Pulp` is not configured to
use `TLS`.

Signed-off-by: Jack Hodgkiss <jack@stackhpc.com>

Author: jackhodgkiss

etc/kayobe/container-engine.yml

@@ -40,7 +40,7 @@ docker_registry: "{{ stackhpc_docker_registry }}"
 docker_registry_insecure: "{{ 'https' not in stackhpc_repo_mirror_url }}"
 
 # CA of docker registry
-docker_registry_ca: "{{ kayobe_env_config_path ~ '/openbao/OS-TLS-INT.crt' if pulp_enable_tls | bool else none }}"
+docker_registry_ca: "{{ kayobe_env_config_path ~ '/openbao/OS-TLS-INT.crt' if pulp_enable_tls | bool else '' }}"
 
 # List of Docker registry mirrors.
 #docker_registry_mirrors: