build(before-code-freeze): Prepare the ONNX Runtime backend for the manylinux base

[mc-nv]

What does the PR do?

Prepare the ONNX Runtime backend for the 26.08 manylinux base:

• add setuptools to the RHEL pip list -- ORT's --build_wheel step runs
  setup.py bdist_wheel under the pipx interpreter, and Python 3.12 no longer
  bootstraps setuptools, so the wheel step failed with ModuleNotFoundError.
• switch to the default pipx environment and the env-var form for the Python location.
• copy onnxruntime_error_code.h, new in ORT 1.28.
• bump OpenVINO to 2026.3.

Checklist

• PR title reflects the change and is of format <commit_type>: <Title>
• Changes are described in the pull request.
• Related issues are referenced.
• Populated github labels field
• Added test plan and verified test passes.
• Verified that the PR passes existing CI.
• Verified copyright is correct on all changed files.
• Added succinct git squash message before merging.
• All template sections are filled out.

Commit Type:

• build
• fix

Related PRs:

• build(before-code-freeze): Align CMake configuration with the other repos common#162
• build(before-code-freeze): Export the stub's dynamic symbols when libpython is static python_backend#451
• build(before-code-freeze): Fix manylinux Python version pytorch_backend#204
• build(before-code-freeze): Build against latest upstream container server#8918

Where should the reviewer start?

tools/gen_ort_dockerfile.py.

Test plan:

Covered by the internal RHEL/manylinux pipeline for the 26.08 upstream bump.

• CI Pipeline ID: 61271932

Caveats:

onnxruntime_error_code.h exists only from ORT 1.28 (404 at rel-1.27.0, 200 at
rel-1.28.0). Any job still pinning ORT 1.27 will fail the header copy -- the
non-RHEL path builds server@main, which pins 1.27.0 while server/build.py
defaults to 1.28.0.

Background

Part of the 26.08 "build against latest upstream container" work: the base image
moved to cuda:13.4-devel-manylinux--26.08, which changed the default GCC
toolset, the Python layout and the bundled OpenSSL.

Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

• Resolves: TRI-1650

^{CI (internal): [#61271932](http://tritonserver.local/ci/pipelines/61271932)}

[mc-nv]

@greptileai review

[greptile-apps]

Greptile Summary

The PR updates ONNX Runtime backend image generation for the manylinux-based 26.08 environment.

• Adds OpenVINO 2026.3 metadata.
• Updates Python packaging setup to use the pipx environment and install setuptools.
• Removes an upstream ONNX Runtime cherry-pick and packages the new ONNX Runtime error-code header.

Confidence Score: 4/5

The PR is not yet safe to merge because the previously reported removal of supported historical OpenVINO mappings still causes Dockerfile generation to fail.

The current version map still omits releases from 2024.0.0 through 2025.4.1, so selecting one of those previously accepted versions reaches the unchanged direct map lookup and terminates generation with a KeyError.

Files Needing Attention: tools/gen_ort_dockerfile.py

Important Files Changed

Filename	Overview
tools/gen_ort_dockerfile.py	Updates the generated build environment, OpenVINO metadata, ONNX Runtime checkout, and exported headers for the 26.08 toolchain.

_{Reviews (2): Last reviewed commit: "adding missed package" | Re-trigger Greptile}

[greptile-apps]

Historical OpenVINO mappings removed

When a build passes a previously mapped OpenVINO release from 2024.0.0 through 2025.4.1, the direct OPENVINO_VERSION_MAP lookup now raises KeyError, causing Dockerfile generation to terminate before the image build starts.

The base branch was changed.