Restart lxc-dnsmasq after clearing iptables rules

When a functional test is run against the same host more than once and
iptables rules are managed by lxc-dnsmasq the rules that lxc-dnsmasq
created during the first run are removed, preventing containers from
accessing external networks.

Add a notify to restart the service and recreate the rules.

Change-Id: Ia3b39c7f81d24de10fe23cb000b1253f4b3dcbfd

test-prepare-host.yml

@@ -30,6 +30,7 @@
 
     - name: Clear iptables rules
       shell: "{{ playbook_dir }}/iptables-clear.sh"
+      register: iptables_clear
       tags:
         - skip_ansible_lint
 
@@ -235,3 +236,12 @@
         - network_interfaces_rhel  is changed
         - item.alias is defined
       with_items: "{{ bridges }}"
+
+    - name: Trigger dnsmasq restart
+      command: /bin/true
+      changed_when:
+        - lxc_net_manage_iptables | bool
+        - iptables_clear is defined
+        - iptables_clear is changed
+      notify:
+        - Restart dnsmasq