Restore unicode file name images for legacy img emojis

What does this MR do?

Restore unicode file name images (1F939.png), for legacy img emojis

Was removed in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/9570/diffs#7ff7049c1c8745b54f0a9ef78996f60b38f36268_94_94

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

• Priority of getting into release and rolled out to GitLab.com
  • https://gitlab.slack.com/archives/releases/p1489649342203345

Why was this MR needed?

Currently emojis cached in the database link to a 404 and break, example with broken legacy emojis, https://gitlab.com/gitlab-org/gitlab-ce/issues/28037

<img class="emoji" title=":juggling:" alt=":juggling:" src="https://gitlab.com/assets/1F939-1f5dafa78de8b37f3df88fdf3084d2380666bd74ab2f449754d8724f6f8dbfa5.png" height="20" width="20" align="absmiddle">

We have since moved to emoji name images files wink.png for fallbacks. I mistakenly assumed we didn't need the previous unicode file name versions anymore.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• 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 it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?