- images.draw_prompt_matrix() should be called with the final width/height
of the generated images, after upscaling.
Otherwise, the number of rows/cols computed in images.draw_grid_annotations
will increase by the upscaling factor.
- Round the number of cols/rows in images.draw_grid_annotations, since
the final images width may be a bit less than the required
hr_upscale_to_x/y