Fix/issue 15798 graceful shutdown

[arunikayadav42]

What is the purpose of the change?

Fixes #15798.
Problem:
In Spring Boot applications, Dubbo currently destroys the ModuleModel immediately upon receiving the ContextClosedEvent. This causes a race condition where other beans (e.g., scheduled tasks or other DisposableBean implementations) that are still destroying themselves may try to call Dubbo services, resulting in RpcException: Directory of type RegistryDirectory already destroyed for service.
Solution:
Refactored DubboDeployApplicationListener to implement DisposableBean and moved the destruction logic from onContextClosedEvent to the destroy() method. This defers Dubbo's shutdown until the bean destruction phase, ensuring that other beans have time to complete their cleanup while Dubbo services are still available, effectively supporting a graceful shutdown.

Checklist

• Make sure there is a GitHub_issue field for the change.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction. (Added GracefulShutdownTest.java in this PR)
• Make sure gitHub actions can pass. Why the workflow is failing and how to fix it?

[zrlw]

1. should use log.info (log4j2.xml) instead of System.out.XXX
2. code format issue should be fixed by mvn spotless:apply