Expand nvidia-smi symlink resolution to additional host paths

[vishalanarase]

Description

Fixes #2506.

PR #2464 updated host nvidia-smi validation to resolve symlinks under /usr/bin/nvidia-smi using pathrs.OpenInRoot. Review feedback noted that other common locations are also used in the wild and should be searched in a follow-up:

• /usr/sbin/nvidia-smi — Talos and similar distros
• /usr/lib/wsl/lib/nvidia-smi — WSL

This change expands resolveHostNvidiaSMI to search multiple host paths (aligned with getNvidiaSMIPath() in find.go and the DRA driver prestart script):

/opt/bin/nvidia-smi
/usr/bin/nvidia-smi
/usr/sbin/nvidia-smi
/bin/nvidia-smi
/sbin/nvidia-smi
/usr/lib/wsl/lib/nvidia-smi

Each path is resolved via pathrs.OpenInRoot, so symlink handling remains scoped to the mounted host root. The function now returns the resolved path, and validateHostDriver / runValidation use that path in chroot instead of relying on PATH lookup.

Checklist

• No secrets, sensitive information, or unrelated changes
• Lint checks passing (make lint)
• Generated assets in-sync (make validate-generated-assets)
• Go mod artifacts in-sync (make validate-modules)
• Test cases are added for new code paths

Testing

Unit tests added/extended in cmd/nvidia-validator/main_test.go (TestResolveHostNvidiaSMI), covering:

• nvidia-smi present at each search path (/opt/bin, /bin, /usr/bin, /usr/sbin, WSL)
• Symlink resolution for /usr/bin, /usr/sbin, and WSL paths
• Search order preference when multiple paths exist
• Error when nvidia-smi is missing or resolves outside the host root

go test ./cmd/nvidia-validator -run TestResolveHostNvidiaSMI -v

Note: pathrs-lite is Linux-only (//go:build linux), so tests must be run on Linux or via Docker:

❯ docker run --rm \
  -v "$(pwd)":/src -w /src \
  golang:1.26.3 \
  go test ./cmd/nvidia-validator -run TestResolveHostNvidiaSMI -v
=== RUN   TestResolveHostNvidiaSMI
=== RUN   TestResolveHostNvidiaSMI/nvidia-smi_exists_in_/usr/bin
=== RUN   TestResolveHostNvidiaSMI/nvidia-smi_exists_through_absolute_/usr/bin_symlink
=== RUN   TestResolveHostNvidiaSMI/nvidia-smi_exists_through_relative_/usr/bin_symlink
=== RUN   TestResolveHostNvidiaSMI/nvidia-smi_exists_in_/opt/bin
=== RUN   TestResolveHostNvidiaSMI/nvidia-smi_exists_in_/bin
=== RUN   TestResolveHostNvidiaSMI/nvidia-smi_exists_in_/usr/sbin
=== RUN   TestResolveHostNvidiaSMI/nvidia-smi_exists_through_absolute_/usr/sbin_symlink
=== RUN   TestResolveHostNvidiaSMI/nvidia-smi_exists_in_WSL_path
=== RUN   TestResolveHostNvidiaSMI/nvidia-smi_exists_through_absolute_WSL_path_symlink
=== RUN   TestResolveHostNvidiaSMI/earlier_search_path_is_preferred_when_multiple_exist
=== RUN   TestResolveHostNvidiaSMI/parent_dir_is_symlink_to_path_not_within_root
=== RUN   TestResolveHostNvidiaSMI/nvidia-smi_does_not_exist
--- PASS: TestResolveHostNvidiaSMI (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/nvidia-smi_exists_in_/usr/bin (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/nvidia-smi_exists_through_absolute_/usr/bin_symlink (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/nvidia-smi_exists_through_relative_/usr/bin_symlink (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/nvidia-smi_exists_in_/opt/bin (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/nvidia-smi_exists_in_/bin (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/nvidia-smi_exists_in_/usr/sbin (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/nvidia-smi_exists_through_absolute_/usr/sbin_symlink (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/nvidia-smi_exists_in_WSL_path (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/nvidia-smi_exists_through_absolute_WSL_path_symlink (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/earlier_search_path_is_preferred_when_multiple_exist (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/parent_dir_is_symlink_to_path_not_within_root (0.00s)
    --- PASS: TestResolveHostNvidiaSMI/nvidia-smi_does_not_exist (0.00s)
PASS
ok      github.com/NVIDIA/gpu-operator/cmd/nvidia-validator     0.012s

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