Update test_in_custom.py

[ideepankarsharma2003]

PR Title: Fix DataLoader Reference, Remove Duplicates & Optimize Inference

Summary of Changes:

✅ Fixed DataLoader Reference: Replaced valid_loader with data_loader for consistency and correctness.
✅ Optimized Inference: Ensured proper indexing and thresholding for attribute predictions.
✅ Fixed Missing Import: Added os import in CustomDataset.
✅ Removed Unused Variables: Eliminated loss_meter and gt_list to improve efficiency.
✅ Improved JSON Output: Restructured prediction storage for better readability.

Code Fix Example:

for step, (imgs, imgname) in enumerate(valid_loader):  # ❌ Incorrect

⬇️

for step, (imgs, imgname) in enumerate(data_loader):  # ✅ Fixed

Why This Matters:

• Prevents NameError if valid_loader is undefined.
• Reduces redundancy and enhances performance.
• Ensures correct attribute mapping and JSON output.

Testing & Verification:

• Confirmed data_loader is properly initialized before usage.
• Validated model inference and attribute predictions.

🚀 Ready for Review! Let me know if any refinements are needed.