src: remove unimplemented method from node.h

This function was not actually available during any part
of the Node 12 release line because it had been removed
earlier (likely accidentally).

Refs: https://github.com/nodejs/node/pull/27220

PR-URL: https://github.com/nodejs/node/pull/30098


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>