Configure model-gateway so it is deployed across multiple zones
this was brought up as something we should improve gitlab-com/gl-infra/production#14455 (comment 1397142544) since model-gateway is only deployed in a single zone.
I'm not sure if there was any specific reason that we are deploying this in a single zone, that decision might have been made before we had more than one replica.
since we don't have any terraform yet, I think it will be as simple as checking the boxes
@AndrasHerczeg Do you see any issue doing this?