Refactor temporary directory generation across scripts and utilities

[bvandermoon]

Description

Refactor temporary directory generation across multiple scripts and utilities to use dynamically created, unique directories instead of static paths.

FIXES: b/510376084

Tests

Verified that all updated scripts and modules securely generate temporary directories without relying on predictable /tmp paths.

Checklist

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• I have made or will make corresponding changes to the doc if needed, including adding new documentation pages to the relevant Table of Contents (toctree directive) as explained in our documentation.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ation/vllm/torchax_converter/validate_converter.py	0.00%	2 Missing ⚠️

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