fix: Change API call encoding

ansible/roles/firstboot/files/ansible_payload/bootstrap/roles/metacluster/tasks/json-server.yml

@@ -21,6 +21,8 @@
       ansible.builtin.uri:
         url: https://version.{{ vapp['metacluster.fqdn'] }}/healthz
         method: GET
+        # This mock REST API -ironically- does not support json encoded body argument
+        body_format: raw
       register: api_readycheck
       until:
         - api_readycheck.json.status is defined
@@ -32,4 +34,3 @@
     ansible.builtin.uri:
       validate_certs: no
       status_code: [200, 201]
-      body_format: json