move min-list-garbage into min-collect-garbage pkg

we don't want it in the same package as min-copy-closure as
that depends on bash

pkgs/min-copy-closure/default.nix

@@ -8,13 +8,11 @@
   buildInputs = [ ];
   propagatedBuildInputs = [ cpio openssh nix ];
   src = ./.;
-  makeFlags = [ "min-list-garbage" ];
   installPhase = ''
     mkdir -p $out/bin
     for i in min-copy-closure liminix-rebuild; do
       echo $i
       cp ''${i}.sh $out/bin/$i
     done
-    cp min-list-garbage $out/bin
   '';
 }