Implement audit events when policy violations detected in merge requests
Audit events are recorded when policy violations are detected in the merge request.
## Verification Steps
* Switch to admin mode and setup audit event streaming
* Doc: https://docs.gitlab.com/administration/compliance/audit_event_streaming/#add-a-new-http-destination
* Localhost path: http://gdk.test:3000/admin/audit_logs?tab=streams
* HTTP Listener: https://pipedream.com/
* Create a project
* Navigate to "Secure =\> Policies =\> New policy"
* Create a `Merge Request Approval` policy
* Create an MR that violates the policy
* Verify that an audit event is recorded for the violation in SPP project
Example setup with policy violation: https://gitlab.com/gitlab-org/security-risk-management/security-policies/team-member-environment/imam-test-group/policy-violations-test/-/merge_requests/1
task