test: remove vulgar language

The FIXME is obsolete as it was meant about a indentation issue
that got fixed a long time ago.

PR-URL: https://github.com/nodejs/node/pull/18395


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>