recreate word table when refreshing counts

The counting touches a large part of the word table, leaving
bloated tables and indexes. Thus recreate the table instead and
swap it in.

nominatim/tokenizer/legacy_tokenizer.py

@@ -210,7 +210,7 @@ class LegacyTokenizer(AbstractTokenizer):
             self._save_config(conn, config)
 
 
-    def update_statistics(self) -> None:
+    def update_statistics(self, _: Configuration) -> None:
         """ Recompute the frequency of full words.
         """
         with connect(self.dsn) as conn: