[Bug]: CubicVertical edge中label位置相反

### Describe the bug / 问题描述

edge配置如下：

```
edge: {
type: "cubic-vertical",
style: {
endArrow: true,
labelText: (e) => (e.data?.value || "") as string,
labelFontSize: 12,
labelAutoRotate: true,
labelPlacement: "end",
labelTextAlign: "start",
labelMaxWidth: "100%",
labelMaxLines: 2,
labelTextOverflow: "ellipsis",
labelFontWeight: 700,
},
}
```

### Reproduction link / 复现链接

_No response_

### Steps to Reproduce the Bug or Issue / 重现步骤

_No response_

### Version / 版本

🆕 5.x

### OS / 操作系统

- [x] macOS
- [ ] Windows
- [ ] Linux
- [ ] Others / 其他

### Browser / 浏览器

- [x] Chrome
- [ ] Edge
- [ ] Firefox
- [ ] Safari (Limited support / 有限支持)
- [ ] IE (Nonsupport / 不支持)
- [ ] Others / 其他

Start by reproducing the issue with the provided G6 edge configuration for the `cubic-vertical` type, focusing on `labelPlacement: "end"`, `labelTextAlign: "start"`, and `labelAutoRotate: true`. Compare the label position with the expected edge direction; done means the label is no longer reversed and the behavior is verified on G6 5.x in Chrome on macOS.

Written by the indexing model from the issue text.