Adding tracing related tests

[ppatierno]

Since the OpenTracing support, we have never had proper tests for tracing.
With the latest OpenTelemetry addition, we have got this ones here https://github.com/strimzi/strimzi-kafka-bridge/tree/main/src/test/java/io/strimzi/kafka/bridge/tracing but anyway these tests just run clients to send and receive messages without checking that tracing information are available. They just check that messages are properly exchanged when tracing is enabled but nothing more.
We should explore a way to check that expected spans are created and tracing information are available.