lib/modules: don't change disabled store paths

[Pacman99]

Motivation for this change

Allows for modules in flakes to be disabled.
Most modules within flakes are referenced as store paths, and I don't think this should break anything, since store paths are always absolute, so there's no reason to append them to modulesPath.
helps with #114131 I don't know if it fixes the problem entirely.

Things done

• ran lib/tests/modules.sh successfully.
• 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 nixpkgs-review --run "nixpkgs-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.

[stale]

I marked this as stale due to inactivity. → More info