Resolve "Diff file headers on 'Compare' not quite right"

What does this MR do?

Corrects spacing issue on comparison page for diff file headers

What are the relevant issue numbers?

Closes #56938 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary\
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the style guides