The test passed KafkaService.java_class_name() (regex kafka\.Kafka)
to Trogdor's ProcessStopFaultSpec, but Trogdor's worker matches
the target JVM by literal substring against jcmd -l.
The escaped form never matched the real kafka.Kafka line,
so SIGSTOP/SIGCONT were sent to zero pids and the leader was never
actually frozen — the scenario passed without testing anything.

Fix by passing the literal main-class name (kafka.Kafka) so the
signal reaches the broker, and verify the fault actually took
effect: assert the broker JVM reaches ps state T (stopped) during
the pause and returns to running after SIGCONT, so any future
no-op fails loudly instead of silently exercising nothing.