Fix img classification tests
Author: nateraw
Pull request: yes

# What does this PR do?

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Fixes unittest issues from #13134. First there was an issue of missing `torchvision`, which was resolved with #13438 , but when that didn't fix it we skipped `test_run_image_classification` with #13451 

Additionally, I added a [test dataset](https://huggingface.co/datasets/hf-internal-testing/cats_vs_dogs_sample) to our internal testing org on huggingface.co, which is what we're using in the test now. Its 50 examples from the `cats_vs_dogs` dataset instead of the 10 that were in the text fixtures before. 

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