Resolve "Handle if Auto DevOps domain is not set"

What does this MR do?

This MR fixes the incorrect behavior of the project settings for Auto DevOps, that cannot make clear what are the consequences of having the domain field set.

To fix this, a warning is shown in the settings page with a description that explains which features will suffer from the absence of the parameter

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

Why was this MR needed?

We need to make it clear to users that enabling Auto DevOps without a Kubernetes cluster and a domain configured will bring Auto Review Apps and Auto Deploy to be disabled.

Screenshots (if relevant)

No problems (everything is configured)

Single message version (with variable message)

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 #37894 (closed)