VirtualBox Guest Additions screen autosize broken (again)

This is 3rd time already VBox autosizing breaks in 0.4.15-dev (see CORE-18169)

Steps to reproduce:

• Install ReactOS BootCD on VirtualBox (tested version 6.1.34)
• Install VirtualBox Guest Additions
• Get to the desktop and maximize or resize VM window
• Expected: Screen size is being adjusted to VM window
• Observed: Screen size is unchanged

It's possible to change screen resolution manually in the Display Properties to make it fit the VM window, just like in the previous ticket.

Debug logs captured with +UserDisplay,+EngLDev,+EngPDev,+EngMDev channels enabled:

• Before: 0.4.15-dev-4558-g185f2da.txt
• After: 0.4.15-dev-4559-g37c2bb3.txt

Cc hpoussin for guilty commits.