Fix KafkaStreamsTest

[smola]

What Does This Do

Fix KafkaStreamsTest. This test was broken after it was marked as @Flaky. Not detected because these do not run in the main CI pipelines.

Test with:

./gradlew :dd-java-agent:instrumentation:kafka-streams-0.11:latestDepTest

Motivation

Additional Notes

Contributor Checklist

• Format the title according the contribution guidelines
• Assign the type: and (comp: or inst:) labels in addition to any usefull labels
• Don't use close, fix or any linking keywords when referencing an issue.
  Use solves instead, and assign the PR milestone to the issue
• Update the public documentation in case of new configuration flag or behavior

Jira ticket: [PROJ-IDENT]