chore: mark generated `runtimeConfig` properties as internal

[BobbieGoede]

🔗 Linked issue

• 2828

❓ Type of change

• [ ] 📖 Documentation (updates to the documentation or readme)
• [ ] 🐞 Bug fix (a non-breaking change that fixes an issue)
• [ ] 👌 Enhancement (improving an existing functionality like performance)
• [ ] ✨ New feature (a non-breaking change that adds functionality)
• [ ] ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

I forgot to mark the runtimeConfig properties as @internal in #2828, is the description clear enough?

📝 Checklist

• [x] I have linked an issue or discussion.
• [ ] I have updated the documentation accordingly.