[improve][broker] Avoid printing log for IncompatibleSchemaException …

…in ServerCnx (#23938)

### Motivation

If the producer is created with some schema error, the broker will print many error logs like this:

```
ERROR org.apache.pulsar.broker.service.ServerCnx - Try add schema failed, remote address xxx
java.util.concurrent.CompletionException: org.apache.pulsar.broker.service.schema.exceptions.IncompatibleSchemaException: Producers cannot connect or send message without a schema to topics with a schemawhen SchemaValidationEnforced is enabled
```

This error can be reported to the client and not need to print it in the broker.

### Modifications

- Avoid printing log for IncompatibleSchemaException in ServerCnx

pulsar-broker/src/main/java/org/apache/pulsar/broker/service/ServerCnx.java

@@ -1627,8 +1627,12 @@ protected void handleProducer(final CommandProducer cmdProducer) {
                                     BrokerServiceException.getClientErrorCode(exception),
                                     message);
                         }
-                        log.error("Try add schema failed, remote address {}, topic {}, producerId {}", remoteAddress,
-                                topicName, producerId, exception);
+                        var cause = FutureUtil.unwrapCompletionException(exception);
+                        if (!(cause instanceof IncompatibleSchemaException)) {
+                            log.error("Try add schema failed, remote address {}, topic {}, producerId {}",
+                                    remoteAddress,
+                                    topicName, producerId, exception);
+                        }
                         producers.remove(producerId, producerFuture);
                         return null;
                     });