=act #15165 should fix out-of-bounds in actor creation
Other than that, also improved failure logging when AIOOB happens in the histogram
Added a test which shows why the updateWithExpectedInterval method
should be preferred too.

Backport from master

Conflicts:
	akka-testkit/src/test/scala/akka/testkit/metrics/reporter/AkkaGraphiteReporter.scala
Merge pull request #15264 from ktoso/port-metrics-kit-fixes-from-master

=tes,act forward port of metricskit / test stability improvements