check_fonts() download to CONFIG_DIR fix

[glenn-jocher]

Follows #7488. Correct bug where fonts were downloading to current working directory rather than global CONFIG_DIR

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

🌟 Summary

Improved font file handling in Ultralytics' YOLOv5 utility functions.

📊 Key Changes

• Font file existence check now uses a consolidated file variable.
• Download log message now references file directly.

🎯 Purpose & Impact

• ✨ Simplified code: Makes the function slightly cleaner and more readable.
• 🛠️ Consistent logging: Ensures the correct file path is displayed when downloading the font file.
• 🚀 User experience: Users are better informed about where the font file is being downloaded to, enhancing clarity.