DRAFT: Adds the vsd_vulnerability_counts feature flag

What does this MR do and why?

Adds the vsd_vulnerability_counts feature flag

• Introduces the vsd_vulnerability_counts to toggle the vulnerability counts on / off in the VSD page
• Updates related jest tests

Screenshots or screen recordings

Not enabled	Enabled

How to set up and validate locally

$ yarn test analytics/dashboard

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.

Related to #383697 (closed)