Fix incorrect disk sizes during VMware VM import (backport #140)

[mergify]

Problem:
When importing virtual machines from VMware vCenter, the vm-import-controller determines disk sizes using nfc.LeaseItem.Size. In some VMware environments this value represents the total provisioned capacity of the VM, not the size of the individual disk.

As a result, each imported disk may incorrectly receive the aggregate VM size, causing PVCs to be over-provisioned and migrations to fail due to insufficient storage.

Solution:
Disk capacities are now determined using the VM hardware configuration retrieved from: mo.VirtualMachine.Config.Hardware.Device For each VirtualDisk, the code reads: VirtualDisk.CapacityInKB and maps disks to lease items using the busNumber.

Related Issue:
harvester/harvester#10167

Test plan:

1. Create a VM with multiple disks with different sizes.
2. Create a VirtualMachineImport resource
3. Check the disk sizes created in Harvester
4. Disk sizes should now match the original VMware disk capacities.

Observations
on the previous PR, we couldn't match the key, so we now matching the busNumber since is unique per controller instance in hardware model.

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This is an automatic backport of pull request #140 done by Mergify.