Show a warning on the projects with a certificate-based cluster

What does this MR do and why?

This MR adds a warning to the project that uses deprecated certificate-based cluster integration. The warning is to be shown only on gitlab.com for the users with the role of maintainer or higher.

Screenshots or screen recordings

Free namespace	Paid namespace

How to set up and validate locally

1. Pretend to be on gitlab.com
2. Navigate to a project that uses a certificate-based integrated cluster.
   • You can add such cluster from the Infrastructure -> Kubernetes clusters page using the Connect a cluster (certificate - deprecated) option in Actions dropdown. If there's not such an option, please enable :certificate_based_clusters feature flag.
   • Fill in the cluster name, API URL, and service token fields with the random strings to get a cluster record.
3. Verify the alert on the top of the project homepage.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Review progress:

• UX review
• backend developer review
• backend maintainer review
• frontend developer review
• frontend maintainer review

Closes to #360411 (closed)