Resolve transient failure in spec/models/user_spec.rb

What does this MR do?

Adds custom, instead of Ffaker generated, attributes to factories for testing search_with_secondary_emails method.

Why was this MR needed?

To prevent transient failures in spec/modles/user_spec.rb

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• [n/a] API support added
• Tests
  • [n/a] 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 #29328 (closed)