tests: crops: Reduce the size of the lores image

Due to a rendering bug, if the lores viewfinder covers the main
viewfinder, updates stall for an unknown reason. Avoid this temporarily
by reducing the preview image resolution.  Also lower the test time
by reducing the number of frames run in each config.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>

tests/crop_test.py

@@ -15,15 +15,14 @@
 
 for m, l in [(False, False), (False, True), (True, False), (True, True)]:
     cfg = picam2.create_video_configuration(main={"size": (1920, 1080), "format": 'XRGB8888', "preserve_ar": m},
-                                            lores={"size": (640, 640), "format": 'XRGB8888', "preserve_ar": l},
+                                            lores={"size": (320, 320), "format": 'XRGB8888', "preserve_ar": l},
                                             display="main")
     picam2.configure(cfg)
     picam2.start(show_preview=True)
 
-    for _ in range(100):
+    for _ in range(50):
         im = picam2.capture_array("lores")
         cv2.imshow("lores", im)
-        cv2.resizeWindow("lores", (640, 640))
         cv2.waitKey(1)
 
     picam2.stop()