Stop referring to utillinux and use util-linux

[tm-drtina]

utillinux is just an alias since 2020 (NixOS/nixpkgs@bc49a08)
In the recent nixpkgs accessing utillinux shows warnings. Unless there is a need to keep compatibility with nixpkgs 20.09 we can remove it, 21.05 already uses util-linux

[justinwoo]

all of these usages are from node2nix so we'd ideally update or replace that

[tm-drtina]

I was testing the changes locally using nix flakes, so I didn't encounter the issues as in CI.
I've switched from import to callPackage to simplify calling node-env.nix and now it should pass even with non-flakes build