Align Task List Checkboxes

What does this MR do?

Aligns task list checkboxes with list bullets.

Are there points in the code the reviewer needs to double check?

SASS variable usage.

Why was this MR needed?

The checkboxes inserted when creating a task list do not align with the list bullets.

#22466 (closed)

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #22466 (closed)