test: remove flaky designation for fixed test

Remove flaky designation for test-worker-eventlooputil fixed in 9dbde1d4.

PR-URL: https://github.com/nodejs/node/pull/35961


Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>