Fixes spawn issue on Hyper-V

The current Hyper-V Technical Preview introduces slight changes
in the data returned by GetVirtualHardDiskSettingData in
Msvm_ImageManagementService.

Co-Authored-By: Adelina Tuvenie <atuvenie@cloudbasesolutions.com>
Change-Id: I830b07efb657acc1486f86a475310f5f4e584a37
Closes-Bug: #1376883