Support High DPI Aurorae decorations

With high DPI we can't use the image size as a logical size directly.

The other change is use of QPainter::drawImage(QRect target, QImage
image, QRect source)

This slightly confusing method uses logical pixels for the target, but
the source rect is in native pixels of the source.

BUG: 422342


(cherry picked from commit af66f39f)