Fix KafkaOutAdapterParserTests race condition

The `Future` for `Producer.send()` can be fulfilled before
we return it (`isDone()`), so `KafkaTemplate` short-circuits
with a `KafkaException`.

* Modify `KafkaOutboundAdapterParserTests.testSyncMode()`
to assert against `KafkaException` which may be thrown earlier
then previously expected `KafkaProducerException`

**Cherry-pick to `5.5.x`**

spring-integration-kafka/src/test/java/org/springframework/integration/kafka/config/xml/KafkaOutboundAdapterParserTests.java

@@ -40,7 +40,7 @@
 import org.springframework.integration.MessageTimeoutException;
 import org.springframework.integration.kafka.outbound.KafkaProducerMessageHandler;
 import org.springframework.integration.test.util.TestUtils;
-import org.springframework.kafka.core.KafkaProducerException;
+import org.springframework.kafka.KafkaException;
 import org.springframework.kafka.core.KafkaTemplate;
 import org.springframework.kafka.core.ProducerFactory;
 import org.springframework.messaging.MessageHandlingException;
@@ -136,7 +136,7 @@ public void close(Duration timeout) {
 
 		assertThatExceptionOfType(MessageHandlingException.class)
 				.isThrownBy(() -> handler.handleMessage(new GenericMessage<>("foo")))
-				.withCauseInstanceOf(KafkaProducerException.class)
+				.withCauseInstanceOf(KafkaException.class)
 				.withRootCauseInstanceOf(RuntimeException.class)
 				.withStackTraceContaining("Async Producer Mock exception");