Resolve "Spec failure in spec/javascripts/pipelines/header_component_spec.js:46 : Expected 'failed Pipeline #123 triggered 4 weeks ago by Foo' to equal 'failed Pipeline #123 triggered 3 weeks ago by Foo'."

What does this MR do?

Changes the spec mock data to use a relative date

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

None

Why was this MR needed?

Make master green again!

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• 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?

Closes #33321 (closed)