Suppressing CIFAR uninformative and annoying download notification

[talcs]

🚀 The feature

The download method at the CIFAR datasets prints to STDOUT Files already downloaded and verified whenever CIFAR10 or CIFAR100 is initiated with download=True.

This is in contrast to other datasets, like MNIST or FashionMNIST, where nothing is printed if the files are already there.

Motivation, pitch

• One of the scenarios of using the download=True flag is when you want the files to be downloaded on the first time, and then reused on other times. It should mean "Only download if something is missing". So using download=False would be a suboptimal workaround.
• Why not always print a message to STDOUT for any operation that succeeds... (like moving a tensor to the GPU, loading data batches, computing loss)? For the same reason it shouldn't be printed here... Seriously, printing INFO log messages directly to STDOUT, while ignoring logging settings, is a bad practice. If the user has chosen a high-verbosity logging settings, then this is okay, but otherwise it is annoying.
• When running massive experiments, this message contaminates the logs with uninformative text.
• This is a little issue of annoyance, but it is clearly a bad practice.

Alternatives

No response

Additional context

No response

[NicolasHug]

Thanks for the report @talcs , agreed we shouldn't print anything. #8681 will fix this.

[talcs]

Hey, thank you for the quick fix.

I just noticed that it also happens in SVHN dataset, but the "problem" comes from the function download_url in datasets/utils.py. It prints print("Using downloaded and verified file: " + fpath). I would remove that too.