EE-Port: Proper icon validator (gitlab-ce!20620)

What does this MR do?

See gitlab-ce!20620 and gitlab-ce#49236

Does this MR meet the acceptance criteria?

• Tests added for this feature/bug
• Conforms to the code review guidelines
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
• [n/a] EE specific content should be in the top level /ee folder
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• [n/a] Conforms to the database guides
• [n/a] If you have multiple commits, please combine them into a few logically organized commits by squashing them
• [n/a] Internationalization required/considered
• [n/a] If paid feature, have we considered GitLab.com plan and how it works for groups and is there a design for promoting it to users who aren't on the correct plan
• [n/a] End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Ref: gitlab-ce#49236