crud组件，同时开启单行底部显示和自动合并单元格，底部显示有问题

#### 描述问题：

crud组件，同时开启单行底部显示和自动合并单元格，底部显示有问题

#### 复现代码：
{
"type": "crud",
"syncLocation": false,
"columns": [
{
"label": "ID",
"type": "text",
"name": "id",
"id": "u:321276b00856",
"placeholder": "-",
"breakpoint": "*"
},
{
"label": "项目ID",
"type": "text",
"name": "pId",
"id": "u:1df441b05aad",
"placeholder": "-",
"breakpoint": "*"
},
{
"label": "项目名称",
"type": "text",
"name": "pName",
"id": "u:6b2091d614dd"
},
{
"label": "合同编号",
"type": "text",
"name": "snum",
"id": "u:1960c2ac7356",
"placeholder": "-"
},
{
"label": "还款日期",
"type": "date",
"name": "payDay",
"id": "u:2e22f202e80b",
"format": "YYYY-MM-DD",
"valueFormat": "YYYY-MM-DD",
"themeConfig": {
}
},
{
"label": "金额",
"type": "input-number",
"name": "payAmount",
"id": "u:260f5acb5518",
"static": true,
"precision": 2,
"keyboard": true,
"step": "",
"kilobitSeparator": true
},
{
"label": "还款状态",
"type": "status",
"name": "flag",
"id": "u:21126bc994e6"
},
{
"type": "operation",
"label": "操作",
"buttons": [
{
"type": "button",
"label": "删除",
"actionType": "ajax",
"level": "danger",
"id": "u:50bb63897a75",
"confirmText": "确定要删除？",
"api": {
"method": "post",
"url": "/admin/delBJPlan"
}
}
],
"id": "u:f4c1ad4b6818",
"name": "op"
}
],
"id": "u:b04ce59948e7",
"filterSettingSource": [
"id",
"pId",
"pName",
"snum",
"payDay",
"payAmount",
"flag"
],
"features": [
"delete",
"update",
"create"
],
"initFetch": false,
"initFetchOn": "",
"rowClassNameExpr": "",
"data": [
{
"id": 1,
"pId": 11,
"pName": "项目名称",
"snum": "1",
"payDay": "2023-11-11",
"payAmount": "1000",
"flag": 1
},
{
"id": 1,
"pId": 11,
"pName": "项目名称",
"snum": "1",
"payDay": "2023-11-11",
"payAmount": "1000",
"flag": 1
}
],
"combineNum": 8,
"messages": {
},
"headerToolbar": [
],
"footerToolbar": [
],
"footable": true
}
######图片

Start by reproducing the issue with the provided CRUD configuration, especially footable and combineNum enabled together, and inspect how the CRUD component renders its bottom display and merged cells. Done means the bottom display remains correct when automatic cell merging and single-row bottom display are enabled together.

Written by the indexing model from the issue text.