GKE Gateway now supports backend authenticated TLS for Gateway-originated

## Feature Feature GKE Gateway now supports backend authenticated TLS for Gateway-originated connections to Pods or InferencePools for the following GatewayClasses: * `gke-l7-global-external-managed` * `gke-l7-regional-external-managed` * `gke-l7-rilb` * `gke-l7-global-regional-managed-mc` * `gke-l7-global-external-managed-mc` ## Issue Issue In GKE version 1.35 and later, workloads that use Workload Identity to[authenticate to Google Cloud APIs](https://cloud.google.com/kubernetes-engine/docs/how-to/workload-identity) might experience transient connectivity timeouts or refused connections to the GKE metadata server immediately following node startup. For recommendations and workarounds, see [Timeout errors at Pod startup](https://cloud.google.com/kubernetes-engine/docs/troubleshooting/authentication#troubleshoot-timeout).