Remove gitops Deprecation Alert

What does this MR do and why?

As the deprecation has been completed, and the functionality turned off, we can remove the alert.

Changelog: removed

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Visit Operate -> Kubernetes clusters page by clicking Connect a cluster button.

2. Create a couple of agents

3. Add configuration files to the agents by creating the file under .gitlab/agents/<your-agent-name>/config.yaml

4. Use gitops keyword in the yaml file, for example

   gitops:
     manifest_projects:
     - id: <your-project-path>

Visit Operate -> Kubernetes clusters page again and verify no alert is shown.

For #440813 (closed)