nix-script: remove phases (#130742)

Co-authored-by: Sandro <[e-mail]>

pkgs/tools/nix/nix-script/default.nix

···
     (haskellPackages.ghcWithPackages (hs: with hs; [ posix-escape ]))
   ];
 
-  phases = [ "buildPhase" "installPhase" "fixupPhase" ];
   buildPhase = ''
+    runHook preBuild
+
     mkdir -p $out/bin
     ghc -O2 $src/nix-script.hs -o $out/bin/nix-script -odir . -hidir .
+
+    runHook postBuild
   '';
   installPhase = ''
+    runHook preInstall
+
     ln -s $out/bin/nix-script $out/bin/nix-scripti
+
+    runHook postInstall
   '';
 
   meta = with lib; {