.optimize() no longer cleans up _docsize

This isn't necessary any more since the new .rebuild_fts()
method can achieve the same thing.

Refs #155, #153

sqlite_utils/db.py

@@ -951,20 +951,6 @@ class Table(Queryable):
                     table=fts_table
                 )
             )
-            self.db.execute(
-                textwrap.dedent(
-                    """
-                DELETE FROM [{table}_docsize] WHERE {column} NOT IN (
-                    SELECT rowid FROM [{table}]);
-            """
-                )
-                .strip()
-                .format(
-                    # FTS5 uses 'id' but FTS4 uses 'docid'
-                    column=self.db["{}_docsize".format(fts_table)].columns[0].name,
-                    table=fts_table,
-                )
-            )
         return self
 
     def search(self, q):