Remove deprecated task in load_dataset

[albertvillanova]

What does this PR do?

Remove deprecated task in load_dataset from tensorflow example. This parameter was deprecated in datasets-2.14.0 one year ago:

• Deprecate task api datasets#5865

Once datasets-3.0 is released, it will raise an error and transformers CI will break.

Fixes #33432

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[LysandreJik]

Thank you!