refactor: Allow use edx_video_id (edxval) in new runtime

This is used to be retroactive in copy-paste videos from Library to Course and Course to Library

xmodule/video_block/video_block.py

@@ -732,8 +732,6 @@ def parse_xml_new_runtime(cls, node, runtime, keys):
             if key not in cls.fields:  # lint-amnesty, pylint: disable=unsupported-membership-test
                 continue  # parse_video_xml returns some old non-fields like 'source'
             setattr(video_block, key, cls.fields[key].from_json(val))  # lint-amnesty, pylint: disable=unsubscriptable-object
-        # Don't use VAL in the new runtime:
-        video_block.edx_video_id = None
         return video_block
 
     @classmethod