Better align fallback image emojis

What does this MR do?

Windows 10, Firefox 55

Before	After

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

Why was this MR needed?

Fallback image emojis had extraneous bottom margin that made misaligned things.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #37147 (closed)