KAFKA-19711: Add commit-rate metric to metered state stores Add commit metric

[bbejeck]

Add commit-rate, commit-latency-avg, and commit-latency-max metrics to replace the flush-* metrics which are now deprecated. Both
sets of metrics are recorded during the deprecation period for backward
compatibility. The flush-* metrics will be removed in the next major
release. Also adds a varargs overload of
StreamsMetricsImpl.maybeMeasureLatency to support recording the same
latency on multiple sensors cleanly.

[eduwercamacaro]

LGTM

[clolov]

The KIP mentions that while the flush metrics are only deprecated, they will no longer record any data under normal use, as Kafka Streams will no longer call StateStore#flush(), but this test seems to assert on a non-zero value. Is not recording flush metrics a next step?

[bbejeck]

Good catch, no my intent was to do it in one step, that detail of the KIP slipped my mind. I'll update it.

[bbejeck]

@clolov I've updated the PR to only record for the commit-X metrics. We need to keep the deprecated flush-X around until the next major release, so I opted to use a dummy value in the init method as workaround for the Spotbugs unused field violation.