openshift_node: Set DOCKER_SERVICE for system container

The node system container was being installed with the DOCKER_SERVICE
holding to it's manifest.json default of docker.service. This change
adds the DOCKER_SERVICE parameter on node system container install
so that it uses the same value from the installer stored in
openshift.docker.service_name.

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1496707

Signed-off-by: Steve Milner <smilner@redhat.com>

roles/openshift_node/tasks/node_system_container.yml

@@ -11,4 +11,5 @@
     image: "{{ 'docker:' if openshift.common.system_images_registry == 'docker' else openshift.common.system_images_registry + '/' }}{{ openshift.node.node_system_image }}:{{ openshift_image_tag }}"
     values:
     - "DNS_DOMAIN={{ openshift.common.dns_domain }}"
+    - "DOCKER_SERVICE={{ openshift.docker.service_name }}.service"
     state: latest