Modify VLC launch command and fullscreen detection

- Add VLC_VERBOSE=-1 to suppress verbose logging in VLC launch commands across multiple example files
- Update is_vlc_fullscreen function to handle cases where screen size or window size is None
- Improve robustness of VLC-related metrics and example configurations

desktop_env/evaluators/metrics/vlc.py

@@ -77,6 +77,10 @@ def is_vlc_recordings_folder(actual_config_path: str, rule: Dict[str, str]) -> f
 
 
 def is_vlc_fullscreen(actual_window_size, screen_size):
+    if screen_size is None or actual_window_size is None:
+        # if the screen size is not available, means that the window is not fullscreen
+        return 0
+
     if actual_window_size['width'] == screen_size['width'] and actual_window_size['height'] == screen_size['height']:
         return 1
     else: