Apply suggestions from code review of branch jpeg-capture-in-stacking

Co-authored-by: Beth Probert <beth_probert@outlook.com>

hardware-specific-tests/picamera2/test_sensor_mode.py

@@ -24,6 +24,9 @@ def test_sensor_mode():
         for size in [(3280, 2464), (1640, 1232)]:
             client.sensor_mode = {"output_size": size, "bit_depth": 10}
             arr = np.array(client.capture_array(stream_name="raw"))
+            # Check that the array dimensions match the requested image size.
+            # Note: Numpy array shape is (y,x), but the sensor is set with (x,y)
+            # hence the need to compare index 0 with index 1.
             assert arr.shape[0] == size[1]