Clean up unsupported threepids from already deactivated users (#5407)

crates/storage-pg/migrations/20260108144040_remove_deactivated_unsupported_threepids.sql

@@ -0,0 +1,13 @@
+-- Copyright 2026 Element Creations Ltd.
+--
+-- SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+-- Please see LICENSE in the repository root for full details.
+
+-- This removes unsupported threepids from deactivated users, as we forgot to do
+-- it in the past. It's fine to do this in a migration as no one is reading from
+-- this table and it is quite small. Follows up from:
+-- https://github.com/element-hq/matrix-authentication-service/pull/5406
+DELETE FROM user_unsupported_third_party_ids
+USING users
+WHERE users.deactivated_at IS NOT NULL
+  AND users.user_id = user_unsupported_third_party_ids.user_id;