test: strengthen test-worker-prof

Force main and worker to stay for some deterministic time
Add some more validation check around profile file generation

Fixes: https://github.com/nodejs/node/issues/26401
PR-URL: https://github.com/nodejs/node/pull/26608



Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>