The test requires High DPI scaling to be disabled since it
manipulates the factors itself in a test.
Turn it off initially and introduce a member variable
containing a suitable size depending on the screen to make the
test pass on High DPI screens without violating minimum window
widths on Windows.
Task-number: QTBUG-76493
Change-Id: I7b908940413d6a35a4bee781b4df07a31069bb17
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
194d4946c7