test: remove the third string literal argument from assert.strictEqual()

Third string literal argument in assert.strictEqual() needs to be
removed. Otherwise, on AssertionError it would not display the
values that failed the check -- this hinders debugging.
The string literals are added as comments above the check.

PR-URL: https://github.com/nodejs/node/pull/21406


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>