Conditionally show policy violation vuln filter

What does this MR do and why?

Conditionally show policy violation vuln filter

• updating Conditionally show policy violation vuln filter (!203902 - merged) to be only for project/group levels
• with feature flag on the project-level and group-level dashboard, show policy violation activity filter
• update tests

EE: true

What does this MR not do and why?

• it does not apply the filter to the backend requests because that work is not complete yet

References

Screenshots or screen recordings

Scenario	Screenshot
Before / FF off
Project
Group
Instance

How to set up and validate locally

1. Upload a GitLab Ultimate license
2. Enable the security_policy_approval_warn_mode feature flag in http://gdk.test:3000/rails/features
3. Navigate to a project with vulnerabilities => Secure => Vulnerability report
4. Verify the user can see an activity filter for policy violations
5. Navigate to a group with a project with vulnerabilities => Secure => Vulnerability report
6. Verify the user can not see an activity filter for policy violations
7. Navigate to the user's 'Your work' section via search bar in sidebar => Security => Vulnerability report (or http://gdk.test:3000/-/security/vulnerabilities/)
8. Verify the user can not see an activity filter for policy violations

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #549786