chore: consider to start ESE spans in the runtime

[franciscolopezsancho]

Such Action subscribing to their events have the ESE as the parent.

So instead of having

KalixEndpoint
  | ESE
  | Action

We would have

KalixEndpoint
   | ESE
      | Action

We could set some value in the trace, in the ESE in the runtime side, that we can then read in the SDK in the:

• ESE and close the span there and then. (not creating a span as we now do. Again, in the SDK side.)
• Action. Just as it's right now. Creating a new span from the trace coming from the event stored in DB. But with the suggestion above pointing to the ESE and not the Kalix Endpoint.