Add missing attribute array validation for TreeEnsembleClassifier

[vraspar]

Description

The TreeEnsembleAttributesV3 constructor in tree_ensemble_attribute.h had 15 ORT_ENFORCE size-validation checks in the regressor path but none in the classifier path. A malformed ONNX model with mismatched TreeEnsembleClassifier attribute arrays (e.g., class_ids vs class_nodeids) could cause out-of-bounds access.

To fix this, moved all ORT_ENFORCE validation checks out of the else (regressor) branch so they apply to both classifier and regressor paths.

[Copilot]

Pull request overview

This PR hardens TreeEnsembleAttributesV3 parsing for TreeEnsembleClassifier by applying the same attribute-array size validations previously only enforced on the regressor path, preventing potential out-of-bounds access from malformed ONNX models.

Changes:

• Move ORT_ENFORCE size/consistency checks to apply to both classifier and regressor attribute parsing.
• Add negative tests ensuring malformed classifier models (mismatched node/class attribute arrays) fail during initialization.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
onnxruntime/test/providers/cpu/ml/tree_ensembler_classifier_test.cc	Adds regression tests that expect failure when classifier attribute arrays are mismatched.
onnxruntime/core/providers/cpu/ml/tree_ensemble_attribute.h	Applies existing attribute array validation checks to classifier path as well as regressor path.

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