remove `url` and `ext` from the return

Instead of set it in return, the extractor will extract the fallback formats if the `formats` length is 0

yt_dlp/extractor/xiaohungsu.py

@@ -55,6 +55,12 @@ class XiaoHungSuIE(InfoExtractor):
                     })
                 })
 
+        if len(formats) == 0:
+            formats.append({
+                'url': self._html_search_meta(['og:video'], webpage),
+                'ext': 'mp4'
+            })
+
         thumbnails = []
         for image_info in traverse_obj(note_info, ('imageList', ...)):
             for url in traverse_obj(image_info, (('urlDefault', 'urlPre'), {url_or_none})):
@@ -65,6 +71,7 @@ class XiaoHungSuIE(InfoExtractor):
                         'width': 'width'
                     })
                 })
+
         return merge_dicts({
             'id': display_id,
             'formats': formats,
@@ -76,7 +83,5 @@ class XiaoHungSuIE(InfoExtractor):
             'uploader_id': ('user', 'userId'),
         }), {
             'title': self._html_search_meta(['og:title'], webpage),
-            'url': self._html_search_meta(['og:video'], webpage),
             'thumbnail': self._html_search_meta(['og:image'], webpage),
-            'ext': 'mp4'
         })