environment: remove sbin from PATH

sbin is a symlink to bin. /run/current-system/sw/sbin and related
profiles only contains packages, which have this symlink. It is a subset
of bin.

nixos/modules/programs/environment.nix

@@ -31,7 +31,7 @@ in
 
     # TODO: move most of these elsewhere
     environment.profileRelativeEnvVars =
-      { PATH = [ "/bin" "/sbin" ];
+      { PATH = [ "/bin" ];
         INFOPATH = [ "/info" "/share/info" ];
         PKG_CONFIG_PATH = [ "/lib/pkgconfig" ];
         TERMINFO_DIRS = [ "/share/terminfo" ];