[CI/Build] Use 127.0.0.1 instead of localhost in utils

[yeqcharlotte]

Purpose

This ensure we set always set default to ipv4, which was causing issues when running the tests on ipv6 hosts.

Test Plan

HF_HUB_DISABLE_XET=1 wp pytest -s -v evals/gsm8k/test_gsm8k_correctness.py --config-list-file=configs/models-small.txt --tp-size=1

Test Result

================================================================================================================= warnings summary ==================================================================================================================
../../../../../../home/yeq/uv_env/vllm/lib64/python3.12/site-packages/torch/cuda/__init__.py:63
  /home/yeq/uv_env/vllm/lib64/python3.12/site-packages/torch/cuda/__init__.py:63: FutureWarning: The pynvml package is deprecated. Please install nvidia-ml-py instead. If you did not install pynvml directly, please report this to the maintainers of the package that instal
led pynvml for you.
    import pynvml  # type: ignore[import]

../../../../../../home/yeq/uv_env/vllm/lib64/python3.12/site-packages/schemathesis/generation/coverage.py:305
  /home/yeq/uv_env/vllm/lib64/python3.12/site-packages/schemathesis/generation/coverage.py:305: DeprecationWarning: jsonschema.exceptions.RefResolutionError is deprecated as of version 4.18.0. If you wish to catch potential reference resolution errors, directly catch refe
rencing.exceptions.Unresolvable.
    ref_error: type[Exception] = jsonschema.RefResolutionError,

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
===================================================================================================== 6 passed, 2 warnings in 429.01s (0:07:09) =====================================================================================================

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.