KIP-187 — Add cumulative count metric for all Kafka rate metrics

Accepted Kafka 1.0 Metrics

Adds a cumulative `total` attribute alongside the existing rate attribute for all JMX rate metrics in Kafka (e.g., `MessagesInPerSec` gains a `total` counter). Kafka's JMX rate metrics expose only the windowed rate, not the running total, whereas tools like Yammer expose both — forcing operators to integrate the rate externally to compute totals.

Details