Remove unnecessary symlinks in /nix/var/nix/gcroots

nixos/modules/services/misc/nix-daemon.nix

···
           /nix/var/nix/gcroots/per-user \
           /nix/var/nix/profiles/per-user \
           /nix/var/nix/gcroots/tmp
-
-        ln -sf /nix/var/nix/profiles /nix/var/nix/gcroots/
-        ln -sf /nix/var/nix/manifests /nix/var/nix/gcroots/
       '';
 
   };