Remove account validity related schema update

Because DINUM had it before mainline, so the file names don't match.
Will need some fiddling with the database before updating to a mainlined
version.

synapse/storage/schema/main/delta/59/12account_validity_token_used_ts_ms.sql

@@ -1,18 +0,0 @@
-/* Copyright 2020 The Matrix.org Foundation C.I.C.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
--- Track when users renew their account using the value of the 'renewal_token' column.
--- This field should be set to NULL after a fresh token is generated.
-ALTER TABLE account_validity ADD token_used_ts_ms BIGINT;