Remove insecure SSL context creation in Triton Python backend

[pravali96]

Issue #, if available: https://t.corp.amazon.com/P346071810, #5372

Summary of Changes

This PR removes the following line from triton_python_backend_utils.py:
ssl._create_default_https_context = ssl._create_unverified_context

Reason for Change

This line globally disabled SSL certificate verification for the Python process.

• Vulnerability: It exposed the container to Man-in-the-Middle (MITM) attacks by allowing connections to servers with invalid or self-signed certificates.
• Technical Debt: It masked potential environment configuration issues (missing CA certs) rather than solving them.

Risk Assessment & Verification

I performed a two-step verification to ensure removing this line does not cause regressions for users downloading models or artifacts at runtime.

1. Functional Regression Test

• Test: Deployed a ResNet50 model using ModelBuilder with the Triton backend.
• Result: The model initialized and performed inference correctly without the SSL bypass.

2. Environment Network Security Test

• Objective: Verify that the underlying Docker image (sagemaker-tritonserver:23.02-py3-cpu) has valid Root CA certificates installed and can perform a standard SSL handshake.
• Method: Executed a direct network call inside the container using urllib without the insecure bypass.
• Command:
  docker run --rm --entrypoint python3 <IMAGE_URI> -c "import urllib.request; print(urllib.request.urlopen('https://www.python.org').getcode())"
• Output:

  TESTING SSL CONNECTIVITY IN CONTAINER...
  Attempting to connect to python.org...
  SUCCESS: Connected with HTTP 200
  SSL Certificates are present.
  

Conclusion

The base image correctly handles SSL verification. The insecure workaround is redundant and unsafe, and has been removed.

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