Parallel edges are invalid when using custom edges

### Describe the bug / 问题描述

需要给边做一些定制，但平行边不生效。
似乎平行边只在不指定edge.type时有效。

### Reproduction link / 重现链接

https://stackblitz.com/edit/react-sqwqhv?file=index.js

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

_No response_

### G6 Version / G6 版本

🆕 5.x

### Operating System / 操作系统

Windows

### Browser / 浏览器

Chrome

### Additional context / 补充说明

_No response_

Start with the linked StackBlitz reproduction at index.js and compare the custom edge configuration with the case where edge.type is omitted. Verify the behavior with parallel edges, then confirm that parallel edges render correctly while using a custom edge type.

Written by the indexing model from the issue text.