Fix var reference

ansible/roles/firstboot/files/ansible_payload/roles/metacluster/tasks/main.yml

@@ -45,14 +45,11 @@
         list_files: yes
       register: imagetarballs
 
-    - ansible.builtin.debug:
-        var: imagetarballs
-
     - name: Import container images
       ansible.builtin.command:
         cmd: k3s ctr image import {{ item }}
         chdir: /opt/metacluster/container_images
-      loop: "{{ imagetarballs.stdout_lines }}"
+      loop: "{{ imagetarballs.files }}"
 
     - name: Delete redundant files
       ansible.builtin.file: