longer `statement_timeout` for migrations - fixes 450

What does this PR do?

as the comment says, migrations are slower than queries done while the server is running, let's give them a longer timeout

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packages/backend/ormconfig.js

@@ -11,7 +11,11 @@ export default new DataSource({
 	username: config.db.user,
 	password: config.db.pass,
 	database: config.db.db,
-	extra: config.db.extra,
+	extra: {
+		...config.db.extra,
+		// migrations may be very slow, give them longer to run (that 10*1000 comes from postgres.ts)
+		statement_timeout: (config.db.extra?.statement_timeout ?? 1000 * 10) * 10,
+	},
 	entities: entities,
 	migrations: ['migration/*.js'],
 });