KafkaSpanDecorator sometimes sets the wrong message_bus.destination tag value

Consider a route like:

from("kafka:foo")
.to("kafka:bar")

When you view the trace span for the producer, the message_bus.destination tag contains "foo". I'd expect it to be "bar" (as that's what we are producing to).

The logic to determine the destination can probably be improved a bit:

https://github.com/apache/camel/blob/main/components/camel-tracing/src/main/java/org/apache/camel/tracing/decorators/KafkaSpanDecorator.java#L52-L59

It looks up an exchange header "kafka.TOPIC". The problem in this particular scenario is that there will be a value present in the exchange passed from the "kafka:foo" consumer. The Kafka header filter will have not yet stripped it when the tracing EventNotifier bits run, so an incorrect value is used for the span name & tag.

Maybe it could always look up the topic name from the endpoint URI options instead of relying on the header.