tools: avoid unnecessary escaping in markdown formatter

Update mdast-util-to-markdown to 1.2.4 which reduces unnecessary
escaping of `_` and some other characters. Re-run markdown formatter.

PR-URL: https://github.com/nodejs/node/pull/40645


Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>