Fix ASR scoring: use score-based threshold instead of passed field

[slister1001]

The sync eval API's 'passed' field indicates whether the eval task completed successfully, NOT whether the content passed a safety check. Using 'not passed' to determine attack success always returns False (since passed=True for successful evals), resulting in 0% ASR even for clearly harmful content (e.g. raw_score=5.0 for violence).

Fix: Replace passed-based logic with score-based threshold comparison matching _evaluation_processor.py. Use get_default_threshold_for_evaluator() (default=3 for 0-7 scale, 0 for binary) and compare raw_score > threshold.

Description

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[Copilot]

Pull request overview

This PR fixes Attack Success Rate (ASR) scoring for RAI sync evaluations by removing reliance on the sync eval API’s passed field (which indicates task completion, not safety pass/fail) and instead determining attack success via a score-vs-threshold comparison consistent with the red team evaluation processor.

Changes:

• Update red team scoring logic to compute attack success as raw_score > get_default_threshold_for_evaluator(metric).
• Remove passed from the red team response/score metadata and stop parsing threshold/passed from sync eval results.
• Update unit tests to validate default-threshold behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
sdk/evaluation/azure-ai-evaluation/azure/ai/evaluation/red_team/_utils/_rai_service_eval_chat_target.py	Switches attack-success logic to default-threshold score comparison and updates emitted metadata.
sdk/evaluation/azure-ai-evaluation/azure/ai/evaluation/red_team/_foundry/_rai_scorer.py	Switches Foundry scorer attack-success logic to default-threshold score comparison; adds severity-label fallback.
sdk/evaluation/azure-ai-evaluation/tests/unittests/test_redteam/test_rai_service_eval_chat_target.py	Aligns expectations with default-threshold scoring and removed passed metadata.
sdk/evaluation/azure-ai-evaluation/tests/unittests/test_redteam/test_foundry.py	Aligns Foundry scorer tests with default-threshold scoring and removed passed/threshold fields.