Hide Koding setting in admin panel if not enabled

What does this MR do?

Starts deprecating Koding in GitLab by preventing new installs from enabling the setting. If Koding is enabled, you can still see and adjust your confirmation, if Koding has not been enabled, it no longer is displayed in settings.

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

No idea?

Why was this MR needed?

To deprecate Koding

Screenshots (if relevant)

With Koding Enabled

Without Koding Enabled

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #30162 (closed)