runtime/metrics: add cleanup and finalizer queue metrics
These metrics are useful for identifying finalizer and cleanup problems,
namely slow finalizers and/or cleanups holding up the queue, which can
lead to a memory leak.
Fixes #72948.
Change-Id: I1bb64a9ca751fcb462c96d986d0346e0c2894c95
Reviewed-on: https://go-review.googlesource.com/c/go/+/690396 Reviewed-by: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Carlos Amedee <carlos@golang.org>
Auto-Submit: Michael Knyszek <mknyszek@google.com>