[BUG] websocket closed refresh data from admin clean plugin local memory

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

when the websocket connection closed between admin and bootstrap, bootsrap refresh local cache data from the admin resend rule data,in this stage, the local cache data is been cleared first and restore one by one ,when the request is arrived this time , we can't find the plugin cache and throw error because we don't finish the cache data refreshing

### Expected Behavior

the refresh cache data staging need reconstructing. can't clear cache data first,we should friendly for the current requesting to the bootstrap

### Steps To Reproduce

_No response_

### Environment

```markdown
ShenYu version(s):2.6.1
```

### Debug logs

_No response_

### Anything else?

_No response_

Start by tracing the WebSocket refresh flow between admin and bootstrap in ShenYu 2.6.1, focusing on how plugin local cache data is cleared and restored. Reproduce the refresh window if possible; done means requests remain serviceable during refresh without a missing-plugin-cache error.

Written by the indexing model from the issue text.