ITS: centralize convert_to_y functions Files affected: tests/scene7/test_multi_camera_switch.py tests/scene8/test_ae_awb_regions.py tests/scene_flash/test_auto_flash.py tests/scene_flash/test_preview_min_frame_rate.py utils/opencv_processing_utils.py Other changes: test_ae_awb_regions.py --> change to RGB conversion from BGR Bug: 333901109, 330382627 Testing: ran on test_multi_camera_switch.py Change-Id: I6ac2cc870c5c5e180ea4ab8c5550ac18b34f916e