test: remove random timer in test-tls-fast-writing

test-tls-fast-writing can fail on a heavily-loaded system due to an
arbitrary 1-second timeout. Remove the arbitrary timeout.

PR-URL: https://github.com/nodejs/node/pull/15138


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>