tools: avoid pending deprecation in doc generator

`unist-util-find` depends on `lodash.iteratee` which uses
`process.binding()`.
Let's remove this dependency which is used in one place to do a very
simple thing.

PR-URL: https://github.com/nodejs/node/pull/37267


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>