Demo App is resetted to the initial Version

[heckelmann]

The current app.js (https://github.com/AloisReitbauer/progressiveDelivery-masterclass/blob/main/demoapp/app.js) is the minimal version of the app without Otel and FF.

Should we revert this commit (AloisReitbauer@4ff275a). I guess it was accidentally overwritten.

[agardnerIT]

This is the case because the documentation states that we built that as we go. So it made no sense to have OTEL and FFs pre-installed. So I removed it to match the documentation.

Now though, with the codespaces approach, it seems we're going for a "already-on" version on first install. So yes, I agree we need to revert to the "already instrumented" app version.