[CI] Extend the use of vcluster

Summary

Currently we only use vcluster to test one K8s version, while all other supported versions are tested on native GKE and EKS clusters. We can reduce the amount of clusters we need to maintain by using vclusters for the majority of our review envionments.

Proposal

• Test all supported K8s versions using vcluster
• Keep one review environment for EKS and GKE to run full QA and to test for distro-specific behavior
• Explore if we can run our ARM test in clusters