KIP-293 — Add new metrics for consumer/replication fetch requests

Discussion MetricsConsumer

Adds separate `FetchRequestsPerSec` metrics on the broker that split consumer client fetch requests from follower replication fetch requests at the topic and broker level. The existing `TotalFetchRequestsPerSec` aggregates both, making it impossible to determine whether a topic is actively being consumed by clients or only by replicas.

Protocol Impact

Fetch

Details