Bump minimum torch version to 2.5 and clean up torch<2.5 workarounds

[cyyever]

What does this PR do?

Bump min torch to 2.5 and remove workarounds.

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CI Security Gate — automatic approval blocked

This PR was not automatically approved for CI because the security gate failed.

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• The PR touches 50 or more files — only PRs with fewer than 50 changed files are automatically approved
• A changed file is outside the allowed directories (src/, tests/, docs/, utils/), has a disallowed extension (only .py, .txt, .md permitted outside tests/ and docs/), or is not .md/.yml inside docs/
• A new high-severity security issue was detected in the changed Python files (Bandit check)

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[github-actions]

[For maintainers] Suggested jobs to run (before merge)

run-slow: cohere2, gemma2, vaultgemma