[Bug] DataZoom preview for multiple x-values incorrect

### Version

5.4.2

### Link to Minimal Reproduction

https://echarts.apache.org/examples/en/editor.html?c=line-simple&code=CYQwLiAEC8kNoChLwIwDYAcaUFYDsATAAwkmQA0RAuuZEqptvsaShdbfXOlroaUQIUAdgFcANuJp1k3RnxYkAzO2lceTfqRXkUJNbI0KBAFgp6O6-c1OryV3jdI47MyFQDcCBAHsADmAAlj7CMJAA3vTiAKYA5tHCwABcEQC-9sigEABaPj4AtimIyMiRJSVgAJ5-0SkA5ADO4oHA0QBOdRnlkA0AFj4A7ilgbaLRXeUNEG1gKUQTJQnJkBYLqfQ09AAeAIJbgQ0pZRXVtZB1QfnRdfTp9JV7B0f0yFU19QBuIOJjnbddDXagWih3gLwi4OQwhAV3qAGUfKI2gBjaIrP7dSBvM51ZrCa4LTLgEApLIgQmQEBtaIgOFVGJHdblO7ITapDxAA

### Steps to Reproduce

* use step data with multiple same x values of type [time, value]
* configure x axis as time
* add dataZoom as slider

### Current Behavior

* dataZoom preview is not in sync with real graph


### Expected Behavior

* steps are shown correctly as rectangular line
* preview is in sync with chart without offset

### Environment

```markdown
- OS: all
- Browser: all
- Framework: official editor / echarts@5.4.2
```

### Any additional comments?

I ran into this issue while creating from normal data step data by adding x/y value pairs.