kubernetes: Uses AWS zone aliases instead of physical zone IDs for locality

AWS zone names are logical and can identify different physical zones across accounts. That is, Account A's us-east-1a is not guaranteed to be Account B's us-east-1a.

AWS also has physical IDs that are consistent across accounts. Account A's use1-az1 is guaranteed to be Account B's use1-az1. These physical IDs are part of AWS EKS nodes from EKS 1.30+ in the node label: topology.k8s.aws/zone-id.

Envoy Gateway currently uses the AWS zone name populated in the standard Kubernetes node label: topology.kubernetes.io/zone when comparing for locality routing, which can route cross-account traffic to the wrong physical zone.

Fixed in #9960

Review #9960, identified as the fix for this issue, and trace the locality-routing comparison described here. Confirm that the implementation uses topology.k8s.aws/zone-id for EKS 1.30+ nodes rather than relying on topology.kubernetes.io/zone across accounts, and verify the resulting behavior with the relevant existing checks.

Written by the indexing model from the issue text.