[Bug 52108] user32:monitor breaks user32:win on Win10 1809

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=52108

--- Comment #2 from François Gouget  ---
That works and it looks like it does not require a logout+login or a reboot to
take effect.

So then would it work to set this registry value at the start of the test and
restore it when it ends? I would prefer that approach as it would make the test
more resilient.