Deduplicate advisory scans for the same advisory

What does this MR do and why?

Deduplicate advisory scans for the same advisory

It's expected for advisory scans to be a long running job, and indempotent. If multiple scans for the same advisory run, the same set of vulnerabilities will have been created making the computational resources used on a no-op. This change prevents this and lessens the load of advisory scans on other Sidekiq workers.

Co-authored-by: Brian Williams bwilliams@gitlab.com

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

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.

Relates to #371063 (closed)