Use groupSnapshotUUID instead of groupSnapshotContentUUID to generate snapshot names

[xing-yang]

What happened:
When generating a snapshot name before calling CSI driver to create a group snapshot, we used groupSnapshotContentUUID:

external-snapshotter/pkg/common-controller/groupsnapshot_controller_helper.go

Lines 559 to 560 in 0f21537

	volumeSnapshotName := getSnapshotNameForVolumeGroupSnapshotContent(
	string(groupSnapshotContent.UID), volumeHandle)

This individual snapshot name is not pass to CSI driver when creating a group snapshot, but some CSI drivers want to know this name. CSI drivers can generate this name, however, they don't know groupSnapshotContentUUID. They only know groupSnapshotUUID.

For the creation of individual VolumeSnapshot, we use content.Spec.VolumeSnapshotRef.UID when generating a snapshot name. Similarly here, we can use groupSnapshotContent.Spec.VolumeGroupSnapshotRef.UID instead of groupSnapshotContent.UID.

https://github.com/kubernetes-csi/external-snapshotter/blob/v8.2.1/pkg/sidecar-controller/csi_handler.go#L87

See discussions here:
https://kubernetes.slack.com/archives/C8EJ01Z46/p1745569386063539?thread_ts=1745569199.407819&cid=C8EJ01Z46

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