[Bug] Empty series symbol 'none' shows 'circle' in legend

### Version

5.6.0

### Link to Minimal Reproduction

https://jsfiddle.net/jq6horg9/3/

### Steps to Reproduce

Just open MRE

### Current Behavior

- When user clicks 'empty' button it shows 'circle' icon in legend and no symbol on graph
- When user clicks any other button it shows actual symbol on graph and in the legend

### Expected Behavior

When user clicks 'empty' button it should show no icon in legend

### Environment

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### Any additional comments?

_No response_