improve merge request widget status icon UX

What does this MR do?

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

for specs, it is probably better to mock the computed properties but I did not know how
computed property logic could also afford some cleanup

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #37229 (closed)