worker: do not emit 'exit' events during process.exit()

Do not emit `'exit'` events caused by recursively stopping all
running Workers from inside the `process.exit()` call.

PR-URL: https://github.com/nodejs/node/pull/32546


Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>