KAFKA-16943: Synchronously verify Connect worker startup failure in InternalTopicsIntegrationTest

[zzzk1]

Synchronously verify worker status when created

Committer Checklist (excluded from commit message)

• Verify design and implementation
• Verify test coverage and CI build status
• Verify documentation (including upgrade notes)

[zzzk1]

@C0urante Could you please take a look? Thank you.

[C0urante]

@zzzk1 Unfortunately, this misses the point of the ticket. If you descend far enough down the call stack for addWorker, you'll see that the DistributedHerder is started, but then begins running on a separate thread. In these tests, we want to verify that that separate thread--which is the "brain" of the worker--has failed with an error. It's not enough to just assert that no workers are running (which I tried to explain on the ticket in the comments section when someone else proposed a similar approach).