test: unmark test-worker-prof as flaky

This has no longer been flaky since V8 7.5.

Refs: https://bugs.chromium.org/p/v8/issues/detail?id=9333
Fixes: https://github.com/nodejs/node/issues/26401

PR-URL: https://github.com/nodejs/node/pull/29511


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>