[BUG] `this.doRefreshConfig()` method is not executed after restarting the plugin.

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

_No response_

### Expected Behavior

_No response_

### Steps To Reproduce

When I open the plugin for the first time, there is no deposit inside `Singleton.INST`, so the following code can be executed:

```java
this.doRefreshConfig(globalLogConfig);
logCollector().start();
```



And it is also possible to execute ``this.close0();`` the first time I close it.


But when I start the plugin again, the `doRefreshConfig()` method will not be executed since it was saved to `Singleton.INST` the previous time.


Also, when closing the plugin, since `isStarted` is not set to `true`, it will not be executed either. This ultimately causes the plugin to fail on subsequent startups and shutdowns.


### Environment

```markdown
ShenYu version(s):2.6.0
```

### Debug logs

_No response_

### Anything else?

My thinking was to `remove` the value inside the `Singleton.INST` when `closing` the plugin. The `doRefreshConfig` method is then executed when the plugin is restarted.

Start by locating the plugin lifecycle code that uses Singleton.INST, doRefreshConfig(), close0(), and isStarted. Reproduce a plugin start, close, and restart with ShenYu 2.6.0, then verify that configuration refresh and shutdown behavior occur on each lifecycle cycle.

Written by the indexing model from the issue text.