Undo the deletion of some tables (#6047)

changelog.d/5893.misc

@@ -1 +1 @@
-Drop some unused tables.
+Stop populating some unused tables.

changelog.d/6047.misc

@@ -0,0 +1,2 @@
+Stop populating some unused tables.
+

synapse/storage/schema/delta/56/drop_unused_event_tables.sql

@@ -1,20 +0,0 @@
-/* Copyright 2019 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.
- */
-
--- these tables are never used.
-DROP TABLE IF EXISTS room_names;
-DROP TABLE IF EXISTS topics;
-DROP TABLE IF EXISTS history_visibility;
-DROP TABLE IF EXISTS guest_access;