[Veeam] Fix restore of reimported VMs

[SadiJr]

Description

Using the VMware hypervisor with the Veeam plugin active, when restoring a VM that has been unmanaged from ACS and reimported, an error occurs because ACS duplicates the register in the database of this VM. This PR aims to fix this behavior.

Types of changes

• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Bug fix (non-breaking change which fixes an issue)
• [ ] Enhancement (improves an existing feature and functionality)
• [ ] Cleanup (Code refactoring and cleanup, that may add test cases)

Feature/Enhancement Scale or Bug Severity

Bug Severity

• [ ] BLOCKER
• [ ] Critical
• [ ] Major
• [x] Minor
• [ ] Trivial

Screenshots (if appropriate):

How Has This Been Tested?

It was tested in a local lab:

1. I created one new VM via ACS, unmanaged this VM, and then reimported this VM again to ACS;
2. I added this VM to one backup offering and made one manual backup;
3. I tried to restore this VM backup;
4. Before ACS failed to restore the VM and duplicate the VM in the UI and database;
5. ACS now completes the restore successfully, and there is no VM duplication.