Custom tree checkboxes have unexpected delayed reaction

1. Open the Pull Requests view from GHPRI
2. Expand a PR
3. Click the checkbox, marking a file as done

:bug: 1 second later, the entire view will get DOM focus, instead of remaining in the checkbox.

https://github.com/microsoft/vscode/assets/22350/32337eba-b8fc-4682-b0f9-cee714e263fa

