10309 Opex: Fix MaxListenersExceededWarning

[Mwindo]

In app.ts and app-public.ts, we run the logging middleware via app.use(logger()). However, the way logger is set up means that we are re-creating our logger--and re-adding related event listeners--on every request. This quickly leads to a MaxListenersExceededWarning (for instance, just refresh the page a few times). This PR fixes the issue by using a closure to create the logger once at app initialization rather than once per request.