Move IaC Scanning UI to CE

What does this MR do and why?

In !73155 (merged), the frontend implementation for enabling IaC scanning via the UI was mistakenly added to EE when it actually should be in CE 🤦

This moves the code back to CE.

Screenshots or screen recordings

	Before	After
EE
CE

How to set up and validate locally

1. Make sure you are running GitLab CE.
2. Enable the configure_iac_scanning_via_mr feature flag.

   Feature.enable(:configure_iac_scanning_via_mr)

3. Visit a project's Security Configuration page at http://127.0.0.1:3000/groups/flightjs/-/security/configuration
4. Click the Configure via Merge Request button in the Infrastructure as Code (IaC) Scanning section.

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.