salt: Make sure container engine is ready before importing nginx

In repo salt state we import the nginx image before creating the
repository manifest. Add a requisite to make the container engine is
ready before importing this nginx container image

salt/metalk8s/repo/installed.sls

@@ -18,11 +18,14 @@
 
 include:
   - .configured
+  - metalk8s.container-engine.running
 
 Inject nginx image:
   containerd.image_managed:
     - name: {{ image_fullname }}
     - archive_path: {{ archives[saltenv].path }}/images/{{ image_name }}-{{ image_version }}.tar
+    - require:
+      - sls: metalk8s.container-engine.running
 
 Install repositories manifest:
   metalk8s.static_pod_managed: