remove lookout dependency

[hui-cha]

Modification:

移除了 Registry Client 对 Lookout 的依赖。

DefaultRegistryClient 中使用 LookoutSubscriber，通过 EventBus 订阅 Registry Client 的事件，来更新 Lookout 中的监控数据。现在移除了 LookoutSubscriber，但是保留了 EventBus。

Summary by CodeRabbit

• New Features

  • No new features introduced.

• Bug Fixes

  • No specific bug fixes noted.

• Refactor

  • Removed the LookoutSubscriber class and its associated functionality, simplifying event handling in the registry client.

• Chores

  • Updated project version from 6.5.1 to 6.5.6.
  • Removed the lookout-api dependency, reducing project complexity.
  • Deleted unit tests related to the LookoutSubscriber class.