Resolve "Change text color of "You can merge this merge request manually..." within MR widget"

What does this MR do?

remove custom text color from MR Widget helptext

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

no

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 #33965 (closed)