INT-3545: Don't AutoStart HeaderChannelRegistry

JIRA: https://jira.spring.io/browse/INT-3545

Previously, the `DefaultHeaderChannelRegistry` was auto-started.
This caused the reaper to run and eventually start all the
`taskScheduler` threads, even if the registry was not being used.

- Defer the `start()` until the first channel is stored.
- Do not start the reaper if the bean has been explicitly stopped.
- Deprecate the implementation of `SmartLifecycle`.

spring-integration-core/src/test/java/org/springframework/integration/channel/registry/HeaderChannelRegistryTests.java

@@ -210,7 +210,6 @@ public class HeaderChannelRegistryTests {
 	public void testExpire() throws Exception {
 		DefaultHeaderChannelRegistry registry = new DefaultHeaderChannelRegistry(50);
 		registry.setTaskScheduler(this.taskScheduler);
-		registry.start();
 		String id = (String) registry.channelToChannelName(new DirectChannel());
 		int n = 0;
 		while (n++ < 100 && registry.channelNameToChannel(id) != null) {