当给被设置为父节点({parent:true})的节点中添加子节点，然后再删除子节点，转换成json时children属性中的数据未清除

### Describe the bug

1、设置一个可以成为父节点的节点，{parent: true}
2、给该父节点放置一个子节点
3、再将该父节点中的子节点删除
4、转换成json数据时，该父节点中的children属性数据未及时清除

### Your Example Website or App

https ://stackoverflow.com/help/mcve

### Steps to Reproduce the Bug or Issue

1、设置一个可以成为父节点的节点，{parent: true}
2、给该父节点放置一个子节点
3、再将该父节点中的子节点删除
4、转换成json数据时，该父节点中的children属性数据未及时清除

### Expected behavior

修正问题描述，及时清除children

### Screenshots or Videos

_No response_

### Platform

- OS: [Windows]
- Browser: [e.g. Chrome, Safari, Firefox]
- Version: [e.g. 91.1]

### Additional context

_No response_

Reproduce the issue in X6 by creating a node with {parent: true}, adding and removing a child, then converting the graph to JSON. Trace the node serialization and child-removal lifecycle; done means the parent’s children data is cleared from the JSON after its last child is deleted.

Written by the indexing model from the issue text.