

You can just use an activation script. Even though technically Windows won’t be activated using the OEM license in a VM, the license is still present on the machine. So legally Windows is still licensed. To get around the thing not automatically activating, an activation script is an easy fix.
This is a good activation script:
One thing to note, if you are using UEFI this is very unlikely to happen. It was designed from the start to have multiple boot options and Windows itself often has multiple entries. It is very rare for a Windows update to mess with any other boot options in UEFI.