test: refactor test-stream-big-push

* use common.mustCall()
* specify setTimeout() duration of 1ms
* remove unused `n` function argument

PR-URL: https://github.com/nodejs/node/pull/10226


Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>