Migrate to autoscaling/v2

API autoscaling/v2beta2 for HorizontalPodAutoscaler is deprecated in v1.23+ and will be unavailable in v1.26+

We have to use autoscaling/v2

NOTES

As described here we need to support clusters as old as 4.6 (kubernetes 1.19). We need to validate that the operator still works under this version.

ACCEPTANCE CRITERIA

• All references to autoscaling/v2beta2 have been replaced by autoscaling/v2
• Kustomize files have been updated accordingly as well
• Operator is capable of deploying Quay in a 4.6 cluster.