[Bug] markLine.data[0].lineStyle.cap invalid

### Version

e.g.5.22

### Link to Minimal Reproduction

https://echarts.apache.org/zh/option.html#series-line.markLine.data.0.lineStyle.cap

### Steps to Reproduce


### Current Behavior

According to the ECharts documentation, the cap property is used to set the line end style (e.g., round represents a rounded end, butt represents a flat end, and square represents a square end). It is expected that after setting this property, the corresponding line ends in the chart will exhibit the corresponding style.

### Expected Behavior

In the actual configuration, regardless of whether the cap property is set to round, butt, or square, the line end style remains unchanged and does not exhibit the expected effect.

### Environment

```markdown
- Browser:

Visit the ECharts official website configuration page ( Official website address ).
In the configuration items, add the relevant configuration of markLine, for example:
```

### Any additional comments?