fix: Maven build for citrus-kafka failing

[christophd]

• Fix Maven build due to embedded Kafka broker starting before old broker has been fully stopped
• Avoids "Address already in use" errors on fast machines
• Remove DirtiesContext for Kafka integration tests to avoid embedded Kafka broker being restarted for each test
• Remove obsolete org.springframework.boot:spring-boot-starter-test dependency in favor of using Citrus ReflectionHelper utils
• Fix citrus-kafka-config-4.4.0-SNAPSHOT.xsd missing changes