JIRA: https://jira.spring.io/browse/INT-4108
Some `Lifecycle.start()/stop()` usage doesn't ensure robustness for components causing unexpected and difficulty tracing issues
* Fix `Lifecycle.start()/stop()` for `FileReadingMessageSource`, `FileWritingMessageHandler`, `AbstractMqttMessageHandler`
* In the `DefaultHeaderChannelRegistry`, `LockRegistryLeaderInitiator`, `MqttPahoMessageHandler` rework logic for shared variables to avoid `NPE`
* Increase receive timeouts in the `PayloadDeserializingTransformerParserTests` and `UdpChannelAdapterTests`
* Prove with the `WatchServiceDirectoryScannerTests` changes that several invocation for `FileReadingMessageSource.start()` are idempotent
**Cherry-pick to 4.3.x**
9101b6a6ef