virtualbox: turn off host resolver and dns proxy
virtualbox: turn off host resolver and dns proxy

This isn't ideal, since it means the VM will likely need a restart when
the host machine moves and DNS changes. But we're running into too many
issues with the host resolver, issues that look similar to
https://www.virtualbox.org/ticket/11663

amazeeio/cachalot,caleb/dinghy,davedevelopment/dinghy,codekitchen/dinghy,rosskevin/dinghy,rosskevin/dinghy,markoshust/dinghy,alexandregz/dinghy,simonnordberg/dinghy,miguelpuyol/dinghy,vultron81/dinghy,vultron81/dinghy,amazeeio/cachalot,tpickett66/dinghy,markoshust/dinghy,chinthakagodawita/dinghy,codekitchen/dinghy,caleb/dinghy,chinthakagodawita/dinghy,miguelpuyol/dinghy,tpickett66/dinghy,simonnordberg/dinghy,alexandregz/dinghy,davedevelopment/dinghy