Revert #178290: nixos/virtualisation: add option

...for explicitly named network interfaces

This reverts commit 6ae3e7695e.
(and evaluation fixups 08d26bbb72 7aed90a969)
Some of the tests fail or time out after the merge.

nixos/modules/virtualisation/qemu-vm.nix

@@ -545,8 +545,7 @@ in
     virtualisation.vlans =
       mkOption {
         type = types.listOf types.ints.unsigned;
-        default = if config.virtualisation.interfaces == {} then [ 1 ] else [ ];
-        defaultText = lib.literalExpression ''if config.virtualisation.interfaces == {} then [ 1 ] else [ ]'';
+        default = [ 1 ];
         example = [ 1 2 ];
         description =
           lib.mdDoc ''
@@ -561,35 +560,6 @@ in
           '';
       };
 
-    virtualisation.interfaces = mkOption {
-      default = {};
-      example = {
-        enp1s0.vlan = 1;
-      };
-      description = lib.mdDoc ''
-        Network interfaces to add to the VM.
-      '';
-      type = with types; attrsOf (submodule {
-        options = {
-          vlan = mkOption {
-            type = types.ints.unsigned;
-            description = lib.mdDoc ''
-              VLAN to which the network interface is connected.
-            '';
-          };
-
-          assignIP = mkOption {
-            type = types.bool;
-            default = false;
-            description = lib.mdDoc ''
-              Automatically assign an IP address to the network interface using the same scheme as
-              virtualisation.vlans.
-            '';
-          };
-        };
-      });
-    };
-
     virtualisation.writableStore =
       mkOption {
         type = types.bool;