tests/ca-less: Use FQCN for ansible.builtin

Use Fully Qualified Collection Name (FQCN) for ansible builtins. This is
ansible.builtin.set_fact instead of set_fact for example and aplies for
all actions that are part of ansible.builtin.

All the replaced ansible.builtins:
  assert, command, copy, debug, fail, fetch, file, import_playbook,
  import_tasks, include_role, include_tasks, include_vars, package,
  set_fact, shell, slurp, stat, systemd

tests/ca-less/clean_up_certificates.yml

@@ -5,7 +5,7 @@
 
   tasks:
   - name: Run generate-certificates.sh
-    command: >
+    ansible.builtin.command: >
       /bin/bash
       generate-certificates.sh delete "{{ item }}"
     args: