test: swap arguments in strictEqual()

Swap arguments in strictEqual() for parallel/test-buffer-copy.

PR-URL: https://github.com/nodejs/node/pull/23204


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>