Part of the preferred split of #433, please check that out if you need
wider context.
This PR adds `ate.workerpool.workers` metric end to end so we have
coverage for workers by pool / state / sandbox class, emitted by ateapi.
Comes with the few attribute keys it actually uses, unit tests, and an
e2e suite that drives an actor lifecycle and checks the metric (plus the
two existing platform metrics) actually lands in the collector.
- [x] Tests pass
- [x] Appropriate changes to documentation are included in the PR
Krisztian F
163bcf4aa8