Test flake chase: MQTT: fix a very timing-sensitive behavior around Last Will and Testament message delivery (backport #15995) (backport #15996)#15999
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When Will-Delay-Interval >= Session-Expiry-Interval, the will queue's x-expires and the will message TTL were only ~5 ms apart. Under a loaded scheduler the queue could be deleted before the dead-letter path ran, silently dropping the will. Extend x-expires by a fixed 1 s margin. Strictly additive; the SessionExpiry = infinity case is unchanged. (cherry picked from commit 6f76113) (cherry picked from commit 25bf953)
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One change is just a bump of an unreasonably short timeout.
Another is a legitimate but very hard to reproduce bug in the MQTT plugin: avoid
a race condition between session expiry and the message expiry timer.
It takes quite a few runs to reproduce unless you pin the runtime to only use one scheduler.
The behavior change is reasonable given how specific the scenario is (two TTLs are at play, and the margin is fixed at 1s).
This is an automatic backport of pull request #15995 done by Mergify.
This is an automatic backport of pull request #15996 done by Mergify.