Importing agents registered an exporter that posted every trace and
span to api.openai.com with the default client's key, so a run against
any other server sent its traces there and logged a 401. Nothing is
registered now. BackendSpanExporter takes the endpoint it posts to, with
no default and no OPENAI_* fallback. set_tracing_export_api_key and
use_for_tracing only fed that upload, so they are gone.
Co-authored-by: Hanzo Dev <[email protected]>