This reverts commit 8cac56c246 and extends
the related comment as the new Windows 11 style actually supports custom
palettes and then wizard's aero style breaks in the same way as with
Fusion.
Apparently this is still problematic leading to errors like
`Qualifying with unknown namespace/class`. It seems that moving the enum to
a different header file works. The trick to use a macro to define
`enum class` ceased to work on the other hand.
Specifying a function with the namespace like
`void QtGui::FinalWizardPage::showResults()` leads to the same problem and
also needs to be avoided.
