Replace go-migrate with morph (#19116)

db/migrations/postgres/000048_create_oauth_apps.down.sql

@@ -0,0 +1,6 @@
+ALTER TABLE oauthapps DROP COLUMN IF EXISTS iconurl;
+ALTER TABLE oauthapps DROP COLUMN IF EXISTS istrusted;
+
+DROP INDEX IF EXISTS idx_oauthapps_creator_id;
+
+DROP TABLE IF EXISTS oauthapps;