omdb commands hang after emitting output when a cockroach node is down #11615

During a self-update of berlin, while one of the cockroach nodes was down due to its sled being rebooted, omdb commands from the switch zone were pretty quick to emit the expected output, but omdb wouldn't exit for several seconds.

I haven't looked into this, although we've seen it before: #10640 (comment) refers to "a different omdb bug where it would hang during shutdown"; I couldn't find a separate issue for that bug, so I opened this one.