Revert "modules: add support for module replacement with disabledModules"

This reverts commit 3f2566689d for now.
Evaluation of the tested job got broken, blocking nixos-unstable.

lib/tests/modules/default.nix

@@ -3,6 +3,5 @@
 {
   inherit (lib.evalModules {
     inherit modules;
-    specialArgs.modulesPath = ./.;
   }) config options;
 }

lib/tests/modules/disable-declare-enable.nix

@@ -1,5 +0,0 @@
-{ lib, ... }:
-
-{
-  disabledModules = [ ./declare-enable.nix ];
-}

lib/tests/modules/disable-define-enable.nix

@@ -1,5 +0,0 @@
-{ lib, ... }:
-
-{
-  disabledModules = [ ./define-enable.nix ];
-}

lib/tests/modules/disable-enable-modules.nix

@@ -1,5 +0,0 @@
-{ lib, ... }:
-
-{
-  disabledModules = [ "define-enable.nix" "declare-enable.nix" ];
-}