System push hooks are never generated

Summary

I've been doing heavier usage of hooks lately for testing some of our infrastructure and I've never seen a system push event. It doesn't look like they're hiding in among push events from webhooks, but I do see test for it (spec/workers/update_merge_requests_worker_spec.rb), however, it does not seem to actually be called anywhere (searching for system_hook_service). Does a call belong in app/services/git_push_service.rb@update_merge_requests where the project push hooks are called?