tests: add _setup_image_processor to QianfanOCR with size=64 and max_patches=1 to reduce memory
Default GotOcr2ImageProcessor uses 448×448 with max_patches=12, producing up to 27 MB
pixel_values per image. Reducing to 64×64 with max_patches=1 cuts peak test RSS ~90 MB.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>