Might resolve
[this](https://github.com/fleetdm/fleet/actions/runs/21648872745/job/62407941749?pr=39201#step:14:14722)
The writer could fire off messages before the subscriber was actually
registered on the NATS server (two separate connections, so no ordering
guarantee).
`nc.Flush()` forces a round-trip to make sure the subscription is in
place before we publish, and `natsWaitOrTimeout` is just a safety net so
we fail in 5s instead of hanging for 20min if something fails.
Nico
3f2b671fb3