Provider traces were being created twice per step:
1. Via `request_async_with_telemetry` / `log_provider_trace_async` in LLMClient
2. Via direct `create_provider_trace_async` calls in LettaAgent
This caused duplicate records in provider_trace_metadata (Postgres) and
llm_traces (ClickHouse) for every agent step.
Removed the redundant direct calls since telemetry is now centralized
in the LLM client layer.
🤖 Generated with [Letta Code](https://letta.com)
Co-authored-by: Letta <noreply@letta.com>
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