[extractor] Standardize _live_title

yt_dlp/extractor/common.py

@@ -3456,10 +3456,8 @@ class InfoExtractor(object):
         return formats
 
     def _live_title(self, name):
-        """ Generate the title for a live video """
-        now = datetime.datetime.now()
-        now_str = now.strftime('%Y-%m-%d %H:%M')
-        return name + ' ' + now_str
+        self._downloader.deprecation_warning('yt_dlp.InfoExtractor._live_title is deprecated and does not work as expected')
+        return name
 
     def _int(self, v, name, fatal=False, **kwargs):
         res = int_or_none(v, **kwargs)