CameraITS:Improve test logging.

Bug: 233691518

Test: Run test locally on pixel device.
Change-Id: I026c24c70d613f3f035f5e9b1da816fdcc14cf5f
diff --git a/apps/CameraITS/utils/video_processing_utils.py b/apps/CameraITS/utils/video_processing_utils.py
index 210e699..7dfd5ad 100644
--- a/apps/CameraITS/utils/video_processing_utils.py
+++ b/apps/CameraITS/utils/video_processing_utils.py
@@ -75,6 +75,8 @@
     if '.png' in file and not os.path.isdir(file) and ffmpeg_image_name in file:
       key_frame_files.append(file)
 
+  logging.debug('Extracted key frames: %s', key_frame_files)
+  logging.debug('Length of key_frame_files: %d', len(key_frame_files))
   if not len(key_frame_files):
     raise AssertionError('No key frames extracted. Check source video.')