🐛 [BUG] Legend focus not working correct on DualAxis charts

Legend focus not working correct on DualAxis charts initially.

Reproduce:
1. Copy "Dual multi line-Example" and add `legend : { radio : true }`
2. Click on a focus button (radio) in the legend
3. Result: Only graphs of the current axis are deselected.
Expected Result: All other graphs will be deselected.
4. Remark: After clicking on different focus buttons on graphs of both axis, all works correct

[Bug-Demo](https://codesandbox.io/s/dualaxis-legend-focus-bug-fevkjw?file=/src/index.js)

* **G2Plot Version**: 2.4.20
* **Platform**: All, including example page

Start with the linked CodeSandbox at src/index.js and reproduce the issue using the “Dual multi line-Example” with legend { radio: true }. Trace the DualAxis legend focus behavior, then verify that selecting a focus button initially deselects graphs on both axes, as shown in the expected result.

Written by the indexing model from the issue text.