Set up a review app for status page branches

It would be nice to be able to easily check that branches have not broken anything visually. Now that we have renovate bot auto-generating MRs for dependency updates, this is even more important.

I'd assume that we can use the autodevops scripts for inspiration. Something where we deploy a docker container might be the easiest. Tanuki-inc is rather similar to the status page (one being a nuxt app, the other being a vue-cli app), we could re-use the dockerfile: https://gitlab.com/gitlab-org/monitor/tanuki-inc/-/blob/master/Dockerfile.

The review app docs details some setup steps for review apps themselves: https://docs.gitlab.com/ee/ci/review_apps/.

Questions/gotchas

• Is there a gitlab-org group-level cluster set up? If not, we may need to add a stand-alone cluster to status-page to have somewhere to deploy to. There is no group level cluster available

Proposal

• Set up a new cluster on the monitoring-development GKE namespace
• Add CI config that automatically creates / tears down review apps