KIP-1322 — Add metrics to Kraft that measure the number of fetch timeouts and election timeouts

Discussion KRaftMetrics

Adds two cumulative gauges to the kafka.raft:type=raft-metrics group, timeout-expirations{timer-name=fetch} and timeout-expirations{timer-name=election}, incremented each time the corresponding raft timer transitions from unexpired to expired during a poll. KRaft leader election and fault recovery hinge on these two timeouts, yet no metric tracked how often they fire, leaving operators without a direct signal for network instability in the metadata quorum.

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