idx_approval_project_rules_on_scan_result_policy_id and idx_approval_merge_request_rules_on_scan_result_policy_id synchronous database indices addition

Summary

This issue is to add a migration to create the idx_approval_project_rules_on_scan_result_policy_id and idx_approval_merge_request_rules_on_scan_result_policy_id database indices synchronously after it has been created on GitLab.com.

The asynchronous index(es) was introduced in !111682 (merged)