Update CheckboxList label() to hiddenLabel()

[bnzo]

This will prevent to display the default label value

Before:

After:

[what-the-diff]

PR Summary

• Improvement in Accessibility of Checkbox List
  The way we identify and label checkbox lists in our app has been tweaked. Instead of using an empty string which might confuse users (especially those using assistive technologies), we've switched to a hidden label. This puts less burden on the user while maintaining the overall look and feel of our application layout.