metric: rework the interface of `ManualWindowedHistogram`

**Is your feature request related to a problem? Please describe.**

The manual histogram currently maintains a cumulative and a windowed histogram. It requires both to be passed in its `Update` function. This is a little cumbersome of an interface to use as the user is expected to maintain both, a cumulative view as well as a windowed view of the metric.

**Describe the solution you'd like**

Ideally, the `Update` function only takes a new windowed histogram and maintains the cumulative values internally. Something like how the batch histogram in Prometheus does it. https://github.com/prometheus/client_golang/blob/3d2cf0b338e19b0eaf277496058fc77bd3add440/prometheus/go_collector_latest.go#L502

Related issues: https://github.com/cockroachdb/cockroach/issues/98266 and https://github.com/cockroachdb/cockroach/issues/98621.

Jira issue: CRDB-25370

Epic CRDB-20790

Start by locating ManualWindowedHistogram and its Update callers, then compare the intended behavior with the linked Prometheus batch histogram implementation. Done means Update accepts only a new windowed histogram while maintaining cumulative values internally, with related tests and callers updated accordingly.

Written by the indexing model from the issue text.