Describe the bug
All values are checked in dropdown if the filter 'by_value' has been set programmatically

To Reproduce
Steps to reproduce the behavior:

1. Set a filter condition 'by_value' programatically on a key-value column
2. Click on the column header to change the filter
3. All boxes are checked even if only one value has been filtered

Expected behavior
The checked boxes should correspond to the displayed values

Stackblitz
https://stackblitz.com/edit/handsontable-key-value-demo-spcjbp

Environment:

• OS: Linux
• Browser: Firefox & Chrome
• Handsontable version: 7.0.0
• Webpack: yes

I have figured out how to fix it, so i will open a PR soon