Revert "modules/virtualisation: add shared options, merge various diskSize options" (#340894)

Breaks evaluation of all nixos tests, and is therefore a channel blocker.

nixos/modules/virtualisation/hyperv-image.nix

@@ -1,37 +1,21 @@
-{
-  config,
-  pkgs,
-  lib,
-  ...
-}:
+{ config, pkgs, lib, ... }:
 
 with lib;
 
 let
   cfg = config.hyperv;
-  virtualisationOptions = import ./virtualisation-options.nix;
-
-in
-{
-
-  imports = [
-    virtualisationOptions.diskSize
-    (lib.mkRenamedOptionModuleWith {
-      sinceRelease = 2411;
-      from = [
-        "virtualisation"
-        "hyperv"
-        "baseImageSize"
-      ];
-      to = [
-        "virtualisation"
-        "diskSize"
-      ];
-    })
-  ];
 
+in {
   options = {
     hyperv = {
+      baseImageSize = mkOption {
+        type = with types; either (enum [ "auto" ]) int;
+        default = "auto";
+        example = 2048;
+        description = ''
+          The size of the hyper-v base image in MiB.
+        '';
+      };
       vmDerivationName = mkOption {
         type = types.str;
         default = "nixos-hyperv-${config.system.nixos.label}-${pkgs.stdenv.hostPlatform.system}";
@@ -50,8 +34,6 @@ in
   };
 
   config = {
-    virtualisation.diskSize = lib.mkDefault (4 * 1024);
-
     system.build.hypervImage = import ../../lib/make-disk-image.nix {
       name = cfg.vmDerivationName;
       postVM = ''
@@ -59,7 +41,7 @@ in
         rm $diskImage
       '';
       format = "raw";
-      inherit (config.virtualisation) diskSize;
+      diskSize = cfg.baseImageSize;
       partitionTableType = "efi";
       inherit config lib pkgs;
     };