This PR updates the GKE managed lustre to:

1. Add Claim_ref to the the PersistentVolume of Managed Lustre. The claimRef field is used by Kubernetes to bind a specific PersistentVolumeClaim (PVC) to a PersistentVolume in static provisioning.
2. Updated capacity_gb to capacity_gib in gke-persistent-volume module to maintain consistency.

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