Only debug when firewalld enabled

We are missing the firewall-cmd executable

Author: jovial

etc/kayobe/environments/ci-aio/hooks/overcloud-host-configure/post.d/10-debug-firewall.yml

@@ -6,3 +6,4 @@
     - name: Configure firewalld to log blocked traffic
       command: firewall-cmd --set-log-denied=all
       become: true
+      when: firewalld_enabled | bool