This is used in constructing the Google OAuth2 login callback URL and has to
match what's configured in Google - also helps if it is actually the address
of the server.

Fewer lines almost always better.  Also, we don't want to spread
these out unless we have to.

Seems this is opt-out:
https://github.com/NixOS/nixpkgs/blob/9d1350d9d56411b685ff3de5839ed6728b1bf808/nixos/modules/services/monitoring/grafana.nix#L576-L582