doc: remove reference to stale CITGM job

Remove reference to job that is out of date, has not
been run for a long time and likely does not work
properly.

Refs: https://github.com/nodejs/citgm/issues/741

PR-URL: https://github.com/nodejs/node/pull/29774


Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>