Upgrade all hosts to release2105 NixOS

Closes privatestorageops#362, privatestorageops#279, and #42

See merge request privatestorage/PrivateStorageio!121

Using AWS is what causes it so using AWS can be what fixes it, too.

The old version of nixpkgs let us get away with setting neither isNormalUser
nor isSystemUser but setting all of the things a normal user would get
directly.  The new version of nixpkgs demands one of these flags be set.  So,
set it, and remove all of the redundant settings that it implies.

Continuous deployment for the grid systems

See merge request privatestorage/PrivateStorageio!115

I hope I'm almost done with this branch.

... This breaks the tie, thx to https://github.com/DBCDK/morph/issues/146

... that don't have it by default. (<5.6)

This was supposed to reduce evaluation-time memory enough to let low-memory
staging servers self-deploy.  But it didn't.

This makes wireguard work on older kernels (19.09 nixos), i.e.
our storage servers currently) and newer kernels (21.05, i.e.
the monitoring server).

Grafana: No phoning home

See merge request privatestorage/PrivateStorageio!119

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

... we'll need this later for the TLS cert.

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