recursive fallback, reduce retry backoff, clean up batch state
- Forward skip_context_check parameter in the 401/403 ephemeral
fallback recursive call to prevent silent early return when
is_tracing_enabled_in_context() is False
- Reduce retry backoff from 1s to 200ms to minimize lock hold time
on the non-first-time path (worst case 400ms vs 2s)
- Add batch state cleanup after _finalize_backend_batch in the
first-time handler, mirroring finalize_batch: reset current_batch,
event_buffer, trace_batch_id, is_current_batch_ephemeral,
batch_owner_type, batch_owner_id, and call _cleanup_batch_data()
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