Add feature flag until vulnerability uuids have been synced.

What does this MR do and why?

Add feature flag until vulnerability uuids have been synced.

This MR disables temporarily what has been introduced by !72405 (merged), however it won't be functional until https://gitlab.com/gitlab-org/gitlab/-/issues/341917 is done.

More details on their relationship can be found #335336 (comment 717918087)

Screenshots or screen recordings

Feature flag disabled

Feature flag enabled

How to set up and validate locally

1. Checkout this branch
2. Follow the steps for Vulnerability-Check

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.