test: remove 3rd arg from to assert.strictEqual()

prevents AssertionError from reporting string literal,
instead displays values of first 2 args passed to
assert.strictEqual()

PR-URL: https://github.com/nodejs/node/pull/21828


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>