fix: import DIR_PARAM_NAME and SAGEMAKER_OUTPUT_LOCATION directly in local/image.py

[egorkosaretsky]

Problem

local/image.py referenced sagemaker.serve.model_builder.DIR_PARAM_NAME and sagemaker.serve.model_builder.SAGEMAKER_OUTPUT_LOCATION via lazy attribute access on the top-level sagemaker module. This relies on sagemaker.serve.model_builder having been imported previously, which is not guaranteed. When using local mode without a prior import of sagemaker.serve.model_builder, this raises:

AttributeError: module 'sagemaker' has no attribute 'serve'

This affects any user of SageMaker local mode in v3 and is the root cause of the issue reported in #5371.

Fix

Import DIR_PARAM_NAME and SAGEMAKER_OUTPUT_LOCATION explicitly at the top of image.py instead of accessing them via the lazy module attribute chain.

Test

Existing local mode unit tests cover the affected code paths.