Reuse nginx configuration for multi-project review apps

Problem to solve

From @ClemMakesApps: Right now, review apps require us to create one nginx server per project. It would be nice to share nginx server configs for multiple projects. On the frontend, we have a review app setup for csslab, gitlab-ui and design-gitlab-com. Those end up being 3 VMs.

Intended users

TBD

Further details

Proposal

Identify a way to more efficiently provision review apps.

Permissions and Security

Documentation

What does success look like, and how can we measure that?

Links / references