This reverts commit 0878ca7.

Motivation for this change

My change to enable JBIG for splix did not work correctly. I was unable to get to the bottom of it because the build never completed. Given that it's also timing out in Hydra (see https://hydra.nixos.org/eval/1372226) I think it's best to simply back it out.

Related to #27027

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• 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 nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.