When OpenTelemetry is configured via the UI, only OTEL_ENDPOINT and
OTEL_HEADERS are set, but OTEL_EXPORTER is not specified. This caused
the exporter to default to "console", meaning traces were printed to
stdout instead of being sent to the configured endpoint.
This fix adds logic in OpenTelemetryConfig.__post_init__ to automatically
infer "otlp_http" as the exporter when an endpoint is specified but the
exporter is still the default "console".
Fixes issue reported by Elastic team where traces weren't being sent
to their OTEL endpoint when configured through the LiteLLM UI.
michelligabriele
1afe3032fd