Remove the retired classic auto-vpa ClusterPolicy and its fixtures #5175

🤖 Generated by the Agentic Engineer

Evidence

#5130 is verified and closed: prod sizes workloads through the three auto-vpa-* GeneratingPolicy objects, and the create and delete cases have both been seen live. The classic auto-vpa ClusterPolicy file was kept in the repository, unregistered, only as the rollback path until that verification. It is still there (k8s/bases/infrastructure/cluster-policies/best-practices/auto-vpa.yaml), along with its classic Kyverno CLI fixtures under tests/auto-vpa/.

Audience and problem

Platform operator: a retired policy left in the tree reads as live configuration. It keeps classic generate rules in the repository that #4984 is working to remove before Kyverno 1.20, and its fixtures keep running in CI against a policy prod no longer uses.

Smallest useful change

Delete the classic file and its classic-only fixtures. Update any reference that still names the classic policy (for example comments in the cluster-policy kustomization or docs). Leave the GeneratingPolicy files and their fixtures untouched.

Acceptance criteria

• No file in the repository defines the classic auto-vpa ClusterPolicy.
• The classic-only fixtures are removed; the GeneratingPolicy fixtures still pass.
• Static validation passes, and a read-only prod readback after deploy still shows one generated VPA per workload.

Size

Small: one deletion PR.