runtime,runtime/metrics: use explicit histogram boundaries
This change modifies the semantics of
runtime/metrics.Float64Histogram.Buckets to remove implicit buckets to
that extend to positive and negative infinity and instead defines all
bucket boundaries as explicitly listed.
Bucket boundaries remain the same as before except
/gc/heap/allocs-by-size:objects and /gc/heap/frees-by-size:objects no
longer have a bucket that extends to negative infinity.
This change simplifies the Float64Histogram API, making it both easier
to understand and easier to use.
Also, add a test for allocs-by-size and frees-by-size that checks them
against MemStats.
Fixes #43443.
Change-Id: I5620f15bd084562dadf288f733c4a8cace21910c
Reviewed-on: https://go-review.googlesource.com/c/go/+/281238
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Austin Clements <austin@google.com> Reviewed-by: Michael Pratt <mpratt@google.com>
Trust: Michael Knyszek <mknyszek@google.com>