Update the usage of credentials in the sagemaker test (apache#41595)

The script run within the sagemaker job imports boto, but doesn't actually use it. This change drops the boto import and removes a lot of the credentials management code in the docker image that's built. This simplifies the system test.

tests/system/providers/amazon/aws/example_sagemaker.py

@@ -77,7 +77,6 @@
 # This script will be the entrypoint for the docker image which will handle preprocessing the raw data
 # NOTE:  The following string must remain dedented as it is being written to a file.
 PREPROCESS_SCRIPT_TEMPLATE = """
-import boto3
 import numpy as np
 import pandas as pd
 
@@ -141,8 +140,6 @@ def _build_and_upload_docker_image(preprocess_script, repository_uri):
             f"""
             FROM public.ecr.aws/amazonlinux/amazonlinux
             COPY {preprocessing_script.name.split('/')[2]} /preprocessing.py
-            ADD credentials /credentials
-            ENV AWS_SHARED_CREDENTIALS_FILE=/credentials
             RUN yum install python3 pip -y
             RUN pip3 install boto3 pandas requests
             CMD [ "python3", "/preprocessing.py"]
@@ -151,13 +148,12 @@ def _build_and_upload_docker_image(preprocess_script, repository_uri):
         dockerfile.flush()
 
         ecr_region = repository_uri.split(".")[3]
+
         docker_build_and_push_commands = f"""
-            cp /root/.aws/credentials /tmp/credentials &&
             # login to public ecr repo containing amazonlinux image (public login is always on us east 1)
             aws ecr-public get-login-password --region us-east-1 |
             docker login --username AWS --password-stdin public.ecr.aws &&
             docker build --platform=linux/amd64 -f {dockerfile.name} -t {repository_uri} /tmp &&
-            rm /tmp/credentials &&
 
             # login again, this time to the private repo we created to hold that specific image
             aws ecr get-login-password --region {ecr_region} |