deploy garage to blue

This configures and deploys Garage, an S3 compatible server, to blue. I configured the metrics endpoint so you can get metrics locally (Prometheus/Grafana live on red), but I think we should bite the bullet and set up a VPN instead of juggling per-application auth across the internet; seems easier to just have a VPN.

We could use this for the backup ring, but it will still be useful even if we don't. For instance, attic also makes use of S3, which would be nice to have.