[improve][test] Restart broker in SimpleProducerConsumerTest if ns deletion times out

[lhotari]

Fixes #20553

Motivation

SimpleProducerConsumerTest is flaky. deleteNamespaceWithRetry often times out. It seems that this became more flaky after #22627.

Modifications

• When the timeout happens, restart the broker.
• rename the method rest() to cleanupAfterMethod()
• capture a thread dump to find out if there's a deadlock when the timeout happens

Documentation

• [ ] doc
• [ ] doc-required
• [x] doc-not-needed
• [ ] doc-complete

[lhotari]

Similar problem in #22736