always download docker image on download_host when download_run_once=true (#5921)

roles/download/tasks/download_container.yml

@@ -59,7 +59,7 @@
       retries: 4
       become: "{{ user_can_become_root | default(false) or not download_localhost }}"
       when:
-        - pull_required
+        - pull_required or download_run_once
         - not image_is_cached
 
     - name: download_container | Save and compress image