There is no need to double the viewport anymore when calculating
orthographic camera frustum visualization, Qt6 correctly accounts
for device pixel ratio in ortho projection. Even in Qt5, the old
hack only made frustum visualization correct for hdpi screens while
breaking it for regular screens.
Also fixed zoom factor handling for orthographic edit camera mode.
Task-number: QDS-5469
Change-Id: Ie53b5dfa2fbcc00f098ea64e5a6673e4b7af0963
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>