service: 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/service/env_vars.yml

@@ -1,15 +1,15 @@
 ---
     - name: Get Domain from server name
-      set_fact:
+      ansible.builtin.set_fact:
         test_domain: "{{ ansible_facts['fqdn'].split('.')[1:] | join('.') }}"
 
     - name: Set host1, host2 and svc hosts fqdn
-      set_fact:
+      ansible.builtin.set_fact:
         host1_fqdn: "{{ 'host1.' + test_domain }}"
         host2_fqdn: "{{ 'host2.' + test_domain }}"
         svc_fqdn: "{{ 'svc.' + test_domain }}"
         nohost_fqdn: "{{ 'nohost.' + test_domain }}"
 
     - name: Get IPv4 address prefix from server node
-      set_fact:
+      ansible.builtin.set_fact:
         ipv4_prefix: "{{ ansible_facts['default_ipv4'].address.split('.')[:-1] | join('.') }}"