Fix MessageDrivenAdapterTests for fetch.min.bytes=46

The real content received by the Kafka consumer is:

Record key bytes - The serialized bytes of each record's key
Record value bytes - The serialized bytes of each record's value (the actual message payload)
Record headers bytes - The serialized bytes of any headers attached to the record
Record metadata overhead - Internal Kafka metadata for each record (offset, timestamp, etc.)
Batch/compression overhead - Additional bytes from batch structures and compression metadata

All of those are contributing to the number of bytes received.
Since we don't have compression and headers, we calculate:
`value + key + timestamp + offset`.
In our test-case it is `23` per record.

Author: artembilan

spring-integration-kafka/src/test/java/org/springframework/integration/kafka/inbound/MessageDrivenAdapterTests.java

@@ -398,7 +398,7 @@ protected boolean doSend(Message<?> message, long timeout) {
 	void testInboundBatch(EmbeddedKafkaBroker embeddedKafka) throws Exception {
 		Map<String, Object> props = KafkaTestUtils.consumerProps(embeddedKafka, "test2", true);
 		props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
-		props.put(ConsumerConfig.FETCH_MIN_BYTES_CONFIG, 24);
+		props.put(ConsumerConfig.FETCH_MIN_BYTES_CONFIG, 46);
 		props.put(ConsumerConfig.FETCH_MAX_WAIT_MS_CONFIG, 2000);
 
 		DefaultKafkaConsumerFactory<Integer, String> cf = new DefaultKafkaConsumerFactory<>(props);