🤔 [QUESTION] 雷达图线条被覆盖。应该如何设置？

### 🐛 Question description [Please make everyone to understand it]
线条被盖住了
### 💻 Link to minimal reproduction
https://codesandbox.io/s/icy-shadow-dzk237?file=/index.ts
Please provide a link by forking these links [g2plot](https://codesandbox.io/s/g2plot-reproduction-template-gyej1) or GitHub repo. What is a minimal reproduction, and why is it required?

### 🏞 Expected result

### 🚑 Any additional [like screenshots]

* **G2Plot Version**:
* **Platform**:

Start with the linked CodeSandbox reproduction at index.ts and compare its radar chart with the expected screenshot. Identify the chart setting or rendering condition that causes one line to be covered, then confirm the intended result in the reproduction; the issue does not specify a version, platform, or requested configuration.

Written by the indexing model from the issue text.