VideoMAE doctest - use valid dummy pixel values
# What does this PR do?

This PR updates the raw input video frames to the expected data type. 

The pixel values passed into the image processor in the tests took values sampled from a standard normal distribution. For an image (or frame) this represents pixels which have been rescaled between [0 - 1] and normalized i.e. one which has already been passed to the image processor. 

After merging #21969, resizing the image throws an error as this image cannot be converted to a PIL.Image.Image without possibly unexpected behaviour from numpy and overflow issues. 


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- [ ] Did you write any new necessary tests?
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