…as deprecated"

This reverts commit c735156.

There is scenarios where polling with high debounce can be used to limit
fetch perf impact (at the cost of high latency).

(cherry picked from commit 03a9f27)

This reverts commit dd4676a.

Will be replaced with 23.3 commit

(cherry picked from commit 7262ff8)

This reverts commit 44bde8d.

Will be replaced with 23.3 commit

(cherry picked from commit 0cacd83)

The `kafka_latency_fetch_latency` metric originally measured the time
it'd take to complete one fetch poll. A fetch poll would create a fetch
plan then execute it in parallel on every shard. On a given shard
`fetch_ntps_in_parallel` would account for the majority of the execution time
of the plan.

Since fetches are no longer implemented by polling there isn't an
exactly equivalent measurement that can be assigned to the metric.

This commit instead records the duration of the first call to
`fetch_ntps_in_parallel` on every shard to the metric. This first call takes
as long as it would during a fetch poll. Hence the resulting measurement
should be close to the duration of a fetch poll.

(cherry picked from commit 44bde8d)
(cherry picked from commit afd1c9a)

(cherry picked from commit de1c248)