refactor(ansible): use ansible_user_id and add root package condition

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@tudattr.dev>

roles/docker_host/tasks/user_group_setup.yml

@@ -5,9 +5,9 @@
     state: present
   become: true
 
-- name: Append the group docker to "{{ user }}"
+- name: Append the group docker to "{{ ansible_user_id }}"
   ansible.builtin.user:
-    name: "{{ user }}"
+    name: "{{ ansible_user_id }}"
     shell: /bin/bash
     groups: docker
     append: true