src: remove duplicate field env in CryptoJob class

Removed field env from cryptojob class, replaced with
function env() inherited from ThreadPoolWork

PR-URL: https://github.com/nodejs/node/pull/31554


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>