iegreview: Provision iegreview application

* Apply role:iegreview to zirconium
* Add vcl to route iegreview.wikimedia.org requests to zirconium
* Configure logstash to store iegreview events received via udp2log

Bug: 71597
RT: 8578
Change-Id: I0c1d670e9d77e6598058f95b792f0c6cb6aa24d0