Force flush handlers after persisting ipsec configuration

This will immediately restart ipsec and attempt to listen for
connections.

In further steps we can force initialization of those connections
to avoid timeouts.

Change-Id: I89b643b563570b0defa74d9e11082806de073f40

tasks/ipsec.yml

@@ -62,3 +62,5 @@
     policy: private-or-clear
     type: "{{ ipsec_type }}"
   when: use_opportunistic_ipsec|bool
+
+- meta: flush_handlers