nixos: remove qtPlugins and gtkPlugins

Both Qt and GTK load plugins from the active profiles
automatically, so it is sufficient to install input methods
system-wide. Overriding the plugin paths may interfere with correct
operation of other plugins.

nixos/modules/module-list.nix

@@ -7,7 +7,6 @@
   ./config/fonts/fonts.nix
   ./config/fonts/ghostscript.nix
   ./config/gnu.nix
-  ./config/gtk-exe-env.nix
   ./config/i18n.nix
   ./config/krb5.nix
   ./config/ldap.nix
@@ -16,7 +15,6 @@
   ./config/nsswitch.nix
   ./config/power-management.nix
   ./config/pulseaudio.nix
-  ./config/qt-plugin-env.nix
   ./config/shells-environment.nix
   ./config/swap.nix
   ./config/sysctl.nix