test: add logging to test-worker-memory

To help troubleshoot CI failures, add some logging.

Refs: https://github.com/nodejs/node/issues/23277#issuecomment-428819187

PR-URL: https://github.com/nodejs/node/pull/23418


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>