Remove reactive-kafka binder

Since the reactor-kafka project has been discontined, we are removing
reactive Kafka binder from Spring Cloud Stream which was already
deprecated on the 4.3.x line.

See: https://spring.io/blog/2025/05/20/reactor-kafka-discontinued

Signed-off-by: Soby Chacko <[email protected]>

Author: sobychacko

binders/kafka-binder/pom.xml

@@ -29,7 +29,6 @@
 		<module>spring-cloud-starter-stream-kafka</module>
 		<module>spring-cloud-stream-binder-kafka-core</module>
 		<module>spring-cloud-stream-binder-kafka-streams</module>
-        <module>spring-cloud-stream-binder-kafka-reactive</module>
 	</modules>
 
 	<dependencies>