Fix fatal log line showing up with publisher not started (#2038)

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> [!IMPORTANT]
> Commented out fatal log line in `get_publish_channel` in
`publisher.rs` to prevent logging when publisher is not started, with a
TODO to revisit logic.
> 
>   - **Logging**:
> - Commented out `baml_log::fatal_once!` in `get_publish_channel` in
`publisher.rs` to prevent fatal log when publisher is not started.
> - Added TODO comment to revisit logic for cases like missing API key.
> 
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Author: aaronvg

engine/baml-runtime/src/tracingv2/publisher/publisher.rs

@@ -54,9 +54,10 @@ fn get_publish_channel(
     {
         let Some(join_handle) = PUBLISHING_TASK.get() else {
             if !allow_missing {
-                baml_log::fatal_once!(
-                    "Tracing publisher not started. Report this bug to the BAML team."
-                );
+                // baml_log::fatal_once!(
+                //     "Tracing publisher not started. Report this bug to the BAML team."
+                // );
+                // TODO: redo this logic -- we dont start the publisher if there's no api key for example.
             }
             return None;
         };