On startup and shutdown of a worker, we log a message of the worker
being started together with a textual representation of a memory
address. Though this can be handy for developers to debug
startup/shutdown sequencing issues of the workers, it's typically not
very useful or informative for an admin. We can also output a lot of
these (on my system I get 265 lines of these during startup).
This changes the messages from Info to Debug, to not print them under
normal circumstances.
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