fix(export): Handle rare cases during INT8_ACQ export

[rajeshgangireddy]

📝 Description

We use dataset (GT) and predictions from model to compare while exporting INT8_ACQ models.
When the metric is image related and not pixel related (which it is by default), we do need to adjust for the cases where gt_mask (from dataset) or anomaly_map (from models) are not present.

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[Copilot]

Pull request overview

This PR fixes handling of optional fields during INT8_ACQ model export by adding conditional checks for anomaly_map, pred_mask, and gt_mask fields that may not always be present when comparing image-level metrics.

Key Changes:

• Added conditional existence checks before accessing anomaly_map and pred_mask from model outputs
• Added conditional check for gt_mask in batch data with proper shape adjustment

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