Add messaging.kafka.write.latency metric using OnBrokerWrite hook with dimension of op (stringified request key). This will allow us to observe more closely if/when Kafka write operations take a long time or if they fail as well, as well as how long it took to do produce operation.
partially fixes TestProducerMetrics. It correctly asserts want metrics.
closes #252 partially fixes #483
messaging.kafka.write.latencymetric usingOnBrokerWritehook with dimension ofop(stringified request key). This will allow us to observe more closely if/when Kafka write operations take a long time or if they fail as well, as well as how long it took to do produce operation.TestProducerMetrics. It correctly assertswantmetrics.