src: remove internalBinding('config').warningFile

Instead use `require('internal/options')` lazily. Also refactor the
call site a bit so that the option is queried only once since it's
synchronous anyway.

PR-URL: https://github.com/nodejs/node/pull/24959


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>