[demo] Set service.name based on the app.kubernetes.io/name value

[rogercoll]

At the moment, the service.name value is set with the value of the well-known app.kubernetes.io/component label.

app.kubernetes.io/component def: The component within the application architecture. Given example: app.kubernetes.io/component: "database"
app.kubernetes.io/name def: The name of the application. A non-unique name.
https://kubernetes.io/docs/reference/labels-annotations-taints/

Sample labels:

Labels:           
                  app.kubernetes.io/component=cartservice
                  app.kubernetes.io/instance=my-otel-demo
                  app.kubernetes.io/name=my-otel-demo-cartservice
                  opentelemetry.io/name=my-otel-demo-cartservice
                  pod-template-hash=5cbd96f4c5

service.name semconv definition: Logical name of the service. MUST be the same for all instances of horizontally scaled services.

If I have multiple otel-demo deployments and I want to scale a specific's deployment services, I would be scaling based on the my-otel-demo-cartservice (app.kubernetes.io/name) value, not on the component's value as it would mean scaling all the cluster deployments. The component label seems a very high level attributes to base the service.name value on.

What do you think if we set the service.name value on the app.kubernetes.io/name label instead?

On going semconv proposal: open-telemetry/semantic-conventions#236

[puckpuck]

We only support installing the demo once within a namespace. Scaling mechanisms should be able to target workloads to specific namespaces only.

[thomheymann]

Based on my findings in https://github.com/elastic/observability-dev/issues/3864#issuecomment-2511471566 this change would also make the service name consistent with the way it is set by Elastic Agent.