test: remove string literal from strictEqual()

Remove 3rd argument from assert.deepStrictEqual() in
test/parallel/test-stream2-writable.js to allow for debugging to work
properly.

PR-URL: https://github.com/nodejs/node/pull/22512


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: George Adams <george.adams@uk.ibm.com>