querystring: remove eslint-disable

Remove the eslint-disable comments by using a strict comparison
instead of a Boolean cast.

PR-URL: https://github.com/nodejs/node/pull/24995


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>