Cancelled host shutdown still aborts running VM

[vad]

1. On Windows 10 host, Run VB virtual machine with Windows 10. Both x64 systems.
2. On the host, initiate system shutdown
3. Observe the message saying that there are active connections in VirtualBox, should the shutdown continue? Press cancel to cancel shutdown.
4. Inspect virtual machine

Expectation: it should continue running as before, since we cancelled shutdown Reality: it's aborted

5. On the host, initiate shutdown again

expectation: no more warning, since the machine is already aborted reality: same warning about active connections

[janitor]

Duplicate of #20112.