Dont re-pin total_seconds as it is already implemented (pandas-dev#17432)

Author: jbrockmendel

pandas/_libs/tslib.pyx

@@ -856,6 +856,9 @@ class NaTType(_NaT):
         return (__nat_unpickle, (None, ))
 
     def total_seconds(self):
+        """
+        Total duration of timedelta in seconds (to ns precision)
+        """
         # GH 10939
         return np.nan
 
@@ -3890,8 +3893,9 @@ for field in fields:
 _nat_methods = ['date', 'now', 'replace', 'to_pydatetime',
                 'today', 'round', 'floor', 'ceil', 'tz_convert',
                 'tz_localize']
-_nan_methods = ['weekday', 'isoweekday', 'total_seconds']
-_implemented_methods = ['to_datetime', 'to_datetime64', 'isoformat']
+_nan_methods = ['weekday', 'isoweekday']
+_implemented_methods = [
+    'to_datetime', 'to_datetime64', 'isoformat', 'total_seconds']
 _implemented_methods.extend(_nat_methods)
 _implemented_methods.extend(_nan_methods)