Add refactor_vulnerability_filters feature flag

What does this MR do and why?

This MR adds the refactor_vulnerability_filters feature flag and adds it to the project, group, and instance vulnerability reports.

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 #376323 (closed)