Fix container scanning configuration page for free tier

What does this MR do and why?

Addresses #365764 (closed)

This change fixes the configuration page for container scanning for free tier. Before this change, the configuration for container scanning cannot be updated for free tiers. But since container scanning is moved to free &2233 (closed), the configuration should also be updatable for free tier.

Screenshots or screen recordings

Before

After

How to set up and validate locally

Navigate to a Free instance of GitLab => a project => Security & Compliance => Configuration

MR acceptance checklist

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