fix(model_builder): Only set s3_upload_path for S3 URIs in passthrough

In _build_for_passthrough(), model_path could be a local /tmp path.
Setting s3_upload_path to a local path caused CreateModel API to reject
the modelDataUrl with a validation error since it requires s3:// or
https:// URIs. Now only S3 URIs are assigned to s3_upload_path; local
paths are handled separately by _prepare_for_mode() in LOCAL_CONTAINER
mode.

Author: nargokul

sagemaker-serve/src/sagemaker/serve/model_builder.py

@@ -1289,10 +1289,10 @@ def _build_for_passthrough(self) -> Model:
 
         self.secret_key = ""
 
-        if not self.model_path:
-            self.s3_upload_path = None
-        else:
+        if self.model_path and self.model_path.startswith("s3://"):
             self.s3_upload_path = self.model_path
+        else:
+            self.s3_upload_path = None
 
         if self.mode in LOCAL_MODES:
             self._prepare_for_mode()