Reduce padding on collapsed diff message

What does this MR do?

Reduce the padding on the collapsed diff message so it takes up less space.

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

Why was this MR needed?

Collapsed diffs took up too much space before.

Screenshots (if relevant)

Before:

After:

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 style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together