Fix aggregated application behavior

* After moving some bunch of beans from the `@EnableBinding` to the
auto-configuration for proper conditional lifecycle we need to be sure
that all those support beans are registered for each child context as
it was before after parsing imports on the `@EnableBinding`.
This way add `search = SearchStrategy.CURRENT` for all the conditions
in the `BindingServiceConfiguration`
* Fix `TestSupportBinderConfiguration` to rely only on the `Binder`
instance created once in the parent level.
This way when we use an aggregated application, only the parent context
creates for us a `TestSupportBinder` and all the child contexts reuse it.
* Register `BinderFactory` only once in parent ctx

spring-cloud-stream-integration-tests/src/test/java/org/springframework/cloud/stream/config/aggregate/AggregateApplicationTests.java

@@ -57,6 +57,8 @@ public class AggregateApplicationTests {
 				.poll(5, TimeUnit.SECONDS));
 		Assert.assertThat(received, notNullValue());
 		Assert.assertTrue(received.getPayload().endsWith("processed"));
+
+		context.close();
 	}
 
 	@Configuration