Motivation for this change

These derivations just unzip something and maybe do a little patching, so there's no benefit to sending the zip file off to a build server and then downloading the unzipped results again.

Things done

I've just done minimal testing that nix-build still works; I really hope changing preferLocalBuilds doesn't affect behavior of the built package or anything that depends on it 😅

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.