FIX: properly set recording status when store apm span to otel

[wzy9607]

close #1476

[cla-checker-service]

💚 CLA has been signed

[dmathieu]

Thank you for the fix. The problem here is that while the span is marked as recording, it's unusable, since it's a noop.
If we provide a recording span, we should be able to set its attributes.

I have opened #1478.
However, it's not fully synced with the agent's spans/transactions. So if you create a span with the agent, then retrieve it using otel and make changes to it, and finally close the agent one, the changes made on the otel side won't be saved.

[dmathieu]

We decided to go with #1478.