BUG:Images skipped silently when thumbnail generation fails

### Is there an existing issue for this?

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### What happened?

Description
When thumbnail generation fails during image processing, images are silently skipped without any user notification. This leads to images missing from the database without the user knowing why

Problem
In the image_util_prepare_image_records function, when image_util_generate_thumbnail() returns False (indicating thumbnail generation failure), the code simply skips adding the image to image_records without logging any warning or error message. The user has no visibility into which images were skipped or why.

Solution
Added explicit warning logging when thumbnail generation fails, so users are informed about skipped images.
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### Checklist before Submitting

- [ ] Have you updated docs for it?
- [ ] Have you added unit tests?
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