Fix packet expiry error handling

[mkurapov]

Bug Report

Currently, when the sending ILP connector sends a packet and it expires, we end up crashing the node process. This is because the packet expiry check is done via setTimeout, with the callback throwing an error that causes an uncaughtException. This leads to a SIGTERM, and the app crashes/exits.

rafiki/packages/backend/src/payment-method/ilp/connector/core/middleware/expire.ts

Lines 10 to 26 in cd3d893

	export function createOutgoingExpireMiddleware() {
	return async (
	{ request, services: { logger } }: ILPContext,
	next: () => Promise<void>
	): Promise<void> => {
	const { expiresAt } = request.prepare
	const duration = expiresAt.getTime() - Date.now()
	const timeout = setTimeout(() => {
	logger.debug({ request }, 'packet expired')
	throw new TransferTimedOutError('packet expired.')
	}, duration)
	await next().finally(() => {
	clearTimeout(timeout)
	})
	}
	}

Expected behavior

The node process does not crash/exit if a packet from the sending connector expires.

Additional context

setTimeout callbacks are treated in a separate call stack as part of the node event loop, this means they are handled outside of the code where they were registered.