build04: switch to zfs

hosts/build04/configuration.nix

@@ -2,7 +2,7 @@
 {
   imports = [
     inputs.srvos.nixosModules.hardware-hetzner-online-arm
-    inputs.self.nixosModules.disko-raid
+    inputs.self.nixosModules.disko-zfs
     inputs.self.nixosModules.common
     inputs.self.nixosModules.builder
     inputs.self.nixosModules.hercules-ci
@@ -11,8 +11,6 @@
 
   nixCommunity.remote-builder.key = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEmdo1x1QkRepZf7nSe+OdEWX+wOjkBLF70vX9F+xf68 builder";
 
-  nixCommunity.disko.raidLevel = 0; # more disk space, we don't have much state to restore anyway
-
   networking.hostName = "build04";
 
   system.stateVersion = "23.11";