fix(vmop): restore requested virtual disk size from snapshot metadata

[danilrwx]

Description

Restore the original requested VirtualDisk PVC size when restoring VM disks from snapshots.

The change stores vd-original-size in the VolumeSnapshot annotations during VirtualDiskSnapshot creation and uses this annotation when VMOP restores VirtualDisks from snapshot resources. If the annotation is absent, the restore flow keeps the previous behavior.

Why do we need it, and what problem does it solve?

A restored VirtualDisk could be created without the original requested PVC size and rely on the snapshot restore defaults. This could make the restored disk size differ from the size requested by the source VirtualDisk.

Persisting and reading the original size from snapshot metadata makes VMOP restore recreate VirtualDisks with the same requested PVC size as the original disk.

What is the expected result?

1. Create a VirtualDisk with a requested PVC size.
2. Create a VirtualDiskSnapshot for this disk.
3. Restore the VM or disk via VMOP from the snapshot.
4. Verify that the restored VirtualDisk has spec.persistentVolumeClaim.size equal to the original requested size.
5. Verify that the corresponding VolumeSnapshot contains the virtualization.deckhouse.io/vd-original-size annotation.

Checklist

• The code is covered by unit tests.
• e2e tests passed.
• Documentation updated according to the changes.
• Changes were tested in the Kubernetes cluster manually.

Changelog entries

section: vd
type: fix
summary: Restore requested VirtualDisk size from snapshot metadata.
impact_level: low