Remove unused _execute_and_decode from scripts/synapse_port_db

scripts/synapse_port_db

@@ -95,8 +95,6 @@ class Store(object):
     _simple_update_one = SQLBaseStore.__dict__["_simple_update_one"]
     _simple_update_one_txn = SQLBaseStore.__dict__["_simple_update_one_txn"]
 
-    _execute_and_decode = SQLBaseStore.__dict__["_execute_and_decode"]
-
     def runInteraction(self, desc, func, *args, **kwargs):
         def r(conn):
             try: