Update Password In URL rule

• Please check this box if this contribution uses AI-generated content as outlined in the GitLab DCO & CLA

What does this MR do?

I changed the Regex {3,20} to {3,40} since it doesn't detect some secret with longer username string.

What are the relevant issue numbers?

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests updated/added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer