Add E2E test app for node + custom OTEL setup

[mydea]

We do not have a test app to test that we properly support a node app with a custom OTEL setup. We may want to have two different E2E test apps:

### Tasks
- [ ] https://github.com/getsentry/sentry-javascript/pull/12690
- [x] An app using `@opentelemetry/sdk-trace-node` and some more custom tracing setup (e.g. more instrumentation, custom sampler, ....)
- [x] An app using `@opentelemetry/sdk-trace-node` that does not use Sentry for performance at all, but only for errors, and only uses OTEL for trace monitoring.

See: https://docs.sentry.io/platforms/javascript/guides/node/tracing/instrumentation/opentelemetry/#using-a-custom-opentelemetry-setup

[chargome]

@mydea can we close this already? 🤔

[mydea]

jup, I think we are in a good place here now! Thank you 🙏