nixos treewide: don't set MODULE_DIR

nixos/modules/system/boot/kernel.nix

@@ -228,7 +228,6 @@ in
     systemd.services."systemd-modules-load" =
       { wantedBy = [ "multi-user.target" ];
         restartTriggers = [ kernelModulesConf ];
-        environment.MODULE_DIR = "/run/booted-system/kernel-modules/lib/modules";
         serviceConfig =
           { # Ignore failed module loads.  Typically some of the
             # modules in ‘boot.kernelModules’ are "nice to have but
@@ -238,10 +237,6 @@ in
           };
       };
 
-    systemd.services.kmod-static-nodes =
-      { environment.MODULE_DIR = "/run/booted-system/kernel-modules/lib/modules";
-      };
-
     lib.kernelConfig = {
       isYes = option: {
         assertion = config: config.isYes option;

nixos/modules/system/boot/modprobe.nix

@@ -63,8 +63,6 @@ with lib;
         echo ${pkgs.kmod}/bin/modprobe > /proc/sys/kernel/modprobe
       '';
 
-    environment.sessionVariables.MODULE_DIR = "/run/current-system/kernel-modules/lib/modules";
-
   };
 
 }

nixos/modules/system/boot/stage-2-init.sh

@@ -207,6 +207,5 @@ exec {logOutFd}>&- {logErrFd}>&-
 # Start systemd.
 echo "starting systemd..."
 PATH=/run/current-system/systemd/lib/systemd \
-    MODULE_DIR=/run/booted-system/kernel-modules/lib/modules \
     LOCALE_ARCHIVE=/run/current-system/sw/lib/locale/locale-archive \
     exec systemd