fix out of boundary vector per class in SVM (#27952)
### Description
vector_per_class dimension was not verified, it could lead to illegal
memory access
### Motivation and Context
security issue
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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: xadupre <22452781+xadupre@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Tianlei Wu <tlwu@microsoft.com>