Remove needless global config for nixpkgs with outdated nodejs16

I can remove this since specified in each repository

- https://github.com/kachick/wait-other-jobs/blob/5896a734eb29efa6ab2d9a333443de45f1cbfa8a/flake.nix#L11-L19
- https://github.com/kachick/action-typescript-template/blob/1ba6b24261ee5b7b127c86b7a1a0a5dd2f5fedd2/flake.nix#L15-L17