Make sure the k8scluster receiver is watching for hpa v2

[jvoravong]

Description:
I missed adding the hpa v2 to the watcher.

Link to tracking Issue: #20480

Testing:
Added more unit tests. Verified k8s.hpa.* metrics for v2 objects are exporting.
Tested manually with:

• Kubernetes 1.25: Rosa 4.12, Kops on AWS, Minikube

Note:
I haven't been able to stop/catch this warning in Kubernetes 1.25, I couldn't find what was throwing it in the receiver code. This isn't an issue in 1.26. If I can track it down, I'll add another commit.
1 warnings.go:70] autoscaling/v2beta2 HorizontalPodAutoscaler is deprecated in v1.23+, unavailable in v1.26+; use autoscaling/v2 HorizontalPodAutoscaler

[dmitryax]

Thanks @jvoravong!

[salapatt]

The customer updated the Splunk OTC agent to version 0.77.0 and still gets the same error messages.

W0522 06:11:24.226426 1 reflector.go:533] k8s.io/[email protected]/tools/cache/reflector.go:231mailto:[k8s.io/[email protected]/tools/cache/reflector.go:231](https://k8s.io/[email protected]/tools/cache/reflector.go:231): failed to list *v2beta1.HorizontalPodAutoscaler: the server could not find the requested resource
129E0522 06:11:24.226454 1 reflector.go:148] k8s.io/[email protected]/tools/cache/reflector.go:231mailto:[k8s.io/[email protected]/tools/cache/reflector.go:231](https://k8s.io/[email protected]/tools/cache/reflector.go:231): Failed to watch *v2beta1.HorizontalPodAutoscaler: failed to list *v2beta1.HorizontalPodAutoscaler: the server could not find the requested resource