test: remove unnecessary test flags

This commit removes unnecessary flags used when starting
tests via the "// Flags:" directive.

PR-URL: https://github.com/nodejs/node/pull/25277


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>