otel grpc instrumentation not working

There seems to be an [issue with opentelemetry-js](https://github.com/open-telemetry/opentelemetry-js/issues/5301)'s grpc instrumentation. Spans are not created, and therefor baggage is not being propagated.

I've added a [lightweight interceptor](https://github.com/gitops-ci-cd/acme-node/blob/main/src/middleware/metadataInterceptor.js) for the time being, as it's necessary for traffic shaping.