Data Zoom series has gaps while series "connectNulls" is true

### Version
5.1.2

### Reproduction link
[https://codepen.io/mihailtrunov/pen/qBjRpBv](https://codepen.io/mihailtrunov/pen/qBjRpBv)

### Steps to reproduce

1. Set axis types as: X - "time", Y - "value".

2. Define "line" series with data that has some values as undefined.

3. Set "connectNulls" setting for this series to true.

### What is expected?
As the "connectNulls" is true it is expected that data zoom representation will have null values connected similarly to the main chart line rendering.

### What is actually happening?
Data zoom series representation is rendered with gaps regardless of the "connectNulls" value being set.