Exclude slf4j-log4j12 and log4j from spring-kafka-test

[rroesch1]

GH-1966 introduced org.apache.zookeeper:zookeeper as dependency to spring-kafka-test. zookeeper includes the log4j dependencies org.slf4j:slf4j-log4j12 (log4j binding for SLF4J) and log4j:log4j (log4j). Adding slf4j-log4j12 to the test-classpath may harm the logging behaviour during test execution if the application already includes another SLF4J binding.

-> Please exclude org.slf4j:slf4j-log4j12 and log4j:log4j from spring-kafka-test.

(FYI; Zookeeper is a transitive dependency of Kafka 2.x, but slf4j-log4j12 and log4j have been excluded.)

[artembilan]

OK. Since they are excluded from Apache Kafka, let's do that on our side as well!
More over this is just a testing support artifact, so should not harm for the target projects.

Please, consider to contribute the fix: https://github.com/spring-projects/spring-kafka/blob/main/CONTRIBUTING.adoc.

Thank you!