test: fixed typos in napi test

Backport-PR-URL: https://github.com/nodejs/node/pull/19447
PR-URL: https://github.com/nodejs/node/pull/18148


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>