[facebook:set] fix/improve 'user_id' extraction (#7848)

https://github.com/mikf/gallery-dl/issues/7848#issuecomment-3181428631

gallery_dl/extractor/facebook.py

@@ -80,6 +80,8 @@ class FacebookExtractor(Extractor):
             directory["user_id"] = (
                 text.extr(
                     set_page, '"actors":[{"__typename":"User","id":"', '"') or
+                text.extr(
+                    set_page, '"userID":"', '"') or
                 directory["set_id"].split(".")[1])
 
         return directory