bfg-repo-cleaner: deprecate phases

pkgs/applications/version-management/git-and-tools/bfg-repo-cleaner/default.nix

···
     nativeBuildInputs = [ makeWrapper ];
     buildInputs = [ jre ];
 
-    phases = "installPhase";
+    dontUnpack = true;
 
     installPhase = ''
       mkdir -p $out/share/java