test: test bottom-up merge sort in URLSearchParams

The bottom-up iterative stable merge sort is called only when
the length of provided value is larger than 100. Added a test for it.

PR-URL: https://github.com/nodejs/node/pull/11399


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>