fix: restart firewalld only when it was running

in !187 (merged) we enable the firewalld.service and also restart it. But we don't have to restart if it was not enable and running since we only change firewall rule when it was enable and running

ansible/roles/install_node_exporter/tasks/main.yaml

@@ -77,3 +77,6 @@
     name: firewalld
     enabled: true
     state: restarted
+  when:
+    - "'firewalld.service' in ansible_facts.services"
+    - ansible_facts.services["firewalld.service"].state == "running"