treewide: get rid of platforms.allBut

Negative reasoning like `allBut` is a bad idea with an open world of
platforms. Concretely, if we add a new, quite different sort of
platform, existing packages with `allBut` will claim they work on it
even though they probably won't.

pkgs/tools/networking/zerotierone/default.nix

@@ -39,6 +39,6 @@ stdenv.mkDerivation rec {
     homepage = https://www.zerotier.com;
     license = licenses.gpl3;
     maintainers = with maintainers; [ sjmackenzie zimbatm ehmry ];
-    platforms = platforms.allBut [ "i686-linux" ];
+    platforms = platforms.x86_64 ++ platforms.aarch64;
   };
 }