Changed failed status icon for several merge request statuses to warning

What does this MR do?

Changed failed status icon for several merge request statuses to warning

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

It's not easy to test this, so review should test each mr widget state 😉

Why was this MR needed?

Failed status icons were not appropriate for the merge request error/warning/message. Also it distracted from more pressing mr-items.

Screenshots (if relevant)

WIP message:

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #36487