fix update scoped routes order problem

[JoeCqupt]

#3896

Route with the same order/priority may be change relative order when the RefreshRoutesEvent trigger to update Scoped route.

reproduce code:

	@Test
	public void updateScopedRoutes() {
		Map<String, Object> metadata = Map.of("metadata-key1", "metadata-value1");
		int order = 0;
		Route route1 = route(1, order, Collections.EMPTY_MAP);
		Route route2 = route(2, order, metadata);
		CachingRouteLocator locator = new CachingRouteLocator(() -> Flux.just(route1, route2));

		List<Route> routes = locator.getRoutes().collectList().block();
		assertThat(routes).containsExactly(route1, route2);

		RefreshRoutesEvent event = new RefreshRoutesEvent(this, metadata);
		locator.onApplicationEvent(event);
		routes = locator.getRoutes().collectList().block();
		assertThat(routes).containsExactly(route1, route2);
	}

	Route route(int id, int order, Map<String, Object> metadata) {
		return Route.async()
			.id(String.valueOf(id))
			.uri("http://localhost/" + id)
			.order(order)
			.predicate(exchange -> true)
			.metadata(metadata)
			.build();
	}

[spencergibb]

Can you add a test that fails without your fix and succeeds with it?

[JoeCqupt]

@spencergibb @ryanjbaxter PTAL