Move user cleanup to firstboot script

ansible/roles/os/tasks/main.yml

@@ -15,6 +15,3 @@
 
 - name: Install ansible
   import_tasks: ansible.yml
-
-- name: Delete temporary users
-  import_tasks: users.yml

ansible/roles/os/tasks/users.yml

@@ -1,5 +0,0 @@
-- name: Delete 'ubuntu' user
-  ansible.builtin.user:
-    name: ubuntu
-    state: absent
-    remove: yes