combo内嵌套input-rich-text,拖动元素改变排序后，富文本框会被清空

#### 描述问题：
combo内嵌套input-rich-text,当"draggable": true,"multiple": true,拖动元素改变排序后，富文本框会清空

#### 截图或视频：

#### 如何复现（请务必完整填写下面内容）：
https://aisuda.github.io/amis-editor-demo/#/edit/0
测试

1. 你是如何使用 amis 的？
{
"type": "combo",
"name": "user",
"label": "用户",
"multiple": true,
"draggable": true,
"items": [
{
"name": "text",
"label": "名字",
"type": "input-rich-text",
"id": "u:a65f79d1bfe3"
},
{
"name": "gender",
"label": "性别",
"type": "select",
"options": [
"男",
"女"
],
}
]
}
]

2. amis 版本是什么？请先在最新 beta 版本测试问题是否存在
6.0.0

3. 粘贴有问题的完整 `amis schema` 代码：

{
"type": "combo",
"name": "user",
"label": "用户",
"multiple": true,
"draggable": true,
"items": [
{
"name": "text",
"label": "名字",
"type": "input-rich-text",
"id": "u:a65f79d1bfe3"
},
{
"name": "gender",
"label": "性别",
"type": "select",
"options": [
"男",
"女"
],
}
]
}
]

4. 操作步骤

拖动元素排序，富文本内容被清空，其他类型正常

Start with the linked amis editor demo and reproduce the issue using the provided combo schema with multiple and draggable enabled. Reorder an item containing input-rich-text and verify that its content is cleared while other item types are not; done means the rich-text content remains after reordering.

Written by the indexing model from the issue text.