Set low custom apdex for project audit events

We've already set low custom apdex for Audit Events features
in https://gitlab.com/gitlab-org/gitlab/-/merge_requests/74942
however we missed setting it for project audit events at that
time.

ee/lib/ee/api/projects.rb

@@ -37,7 +37,7 @@ module EE
 
               use :pagination
             end
-            get '/', feature_category: :audit_events do
+            get '/', feature_category: :audit_events, urgency: :low do
               level = ::Gitlab::Audit::Levels::Project.new(project: user_project)
               audit_events = AuditLogFinder.new(
                 level: level,