remove unused imports

sample-stream/src/main/java/com/redhat/training/kafka/coreapi/RandomPaymentProducer.java

@@ -4,12 +4,10 @@ import java.util.Properties;
 import java.util.Random;
 
 import org.apache.kafka.clients.CommonClientConfigs;
-import org.apache.kafka.clients.producer.Callback;
 import org.apache.kafka.clients.producer.KafkaProducer;
 import org.apache.kafka.clients.producer.Producer;
 import org.apache.kafka.clients.producer.ProducerConfig;
 import org.apache.kafka.clients.producer.ProducerRecord;
-import org.apache.kafka.clients.producer.RecordMetadata;
 import org.apache.kafka.common.config.SslConfigs;
 import org.eclipse.microprofile.config.Config;
 import org.eclipse.microprofile.config.ConfigProvider;