* cleanup: remove unused team arg from registerLastStep
* cleanup: rename promises to ackPromises to make it more clear thats what they are
* cleanup(plugin-server): make waitForAck explicit/required
* add Kafka produce/ack metrics
* Clarify Kafka produce metric/labels
* chore(plugin-server): use librdkafka producer everywhere
We say some 10x improvements in the throughput for session recordings.
Hopefully there will be more improvements here as well, although it's a
little less clear cut.
I don't try to provide any improvements in guarantees around message
production here.
* we still need to enable snappy for kafkajs
* chore(recordings): use cooperative-sticky rebalance strategy
This should make rebalances and lag during deploys a little less
painful. I'm setting this as the globally used strategy, when we e.g.
want to use another strategy for a specific consumer group, we can make
this configurable.
* disable rebalance_callback
* use node-rdkafka-acosom fork instead, for cooperative support
* test(plugin-server): use librdkafka for functional tests
While trying to port the session recordings to use node-librdkafka I
found it useful to first implement it in the functional tests.
* use obj destructuring to make calls more self explanatory
