[Bug] Area Chart - Tooltip Conflicts with Emphasis

### Version

5.6.0

### Link to Minimal Reproduction

https://echarts.apache.org/examples/en/editor.html?c=area-stack

### Steps to Reproduce

1. Using the current Stacked Area Chart example

### Current Behavior

When hovering over a series, emphasis applies to fade the other series and the tooltip appears.
Once this happens, move the cursor within the same series. When you hit another data point for the series, the tooltip remains but emphasis stops applying.

### Expected Behavior

Emphasis should continue being applied as long as the user's cursor is over the series

### Environment

```markdown
n/a
```

### Any additional comments?

_No response_