test: fix assertion argument order

Fix the assertion argument order so that it will report "actual" and
"expected" correctly when the test fails.

Ref: https://github.com/nodejs/node/issues/19263

PR-URL: https://github.com/nodejs/node/pull/19264
Refs: https://github.com/nodejs/node/issues/19263


Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>