use downscaled frames in FGDStatModel test (cherry picked from commit 599f5ef51bfb7a9e71a8c4e50a5f942fb2898cdb)
use downscaled frames in FGDStatModel test
(cherry picked from commit 599f5ef51bfb7a9e71a8c4e50a5f942fb2898cdb)

opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv