util: improve prototype inspection using `inspect()` and `showHidden`

The fast path for the prototype inspection had a bug that caused some
prototype properties to be skipped that should in fact be inspected.

PR-URL: https://github.com/nodejs/node/pull/31113


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>