Merged commit includes the following changes: (#7281)

* Merged commit includes the following changes:
259442882  by hongkuny<hongkuny@google.com>:

    Internal

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259377621  by A. Unique TensorFlower<gardener@tensorflow.org>:

    Fix NCF serialization/de-serialization logic in NCF input pipeline to use tf.FixedLenFeature instead of raw string/binary decoding.

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259373183  by A. Unique TensorFlower<gardener@tensorflow.org>:

    Create binary to generate NCF training/evaluation dataset offline.

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259026454  by isaprykin<isaprykin@google.com>:

    Internal change

258871624  by hongkuny<hongkuny@google.com>:

    Internal change

257285772  by haoyuzhang<haoyuzhang@google.com>:

    Internal change

256202287  by A. Unique TensorFlower<gardener@tensorflow.org>:

    Internal change.

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254069984  by hongkuny<hongkuny@google.com>:
    Automated rollback of changelist 254060732.

254060732  by yifeif<yifeif@google.com>:
    Automated rollback of changelist 254027750.

254027750  by hongkuny<hongkuny@google.com>:

    Internal change

253118910  by hongkuny<hongkuny@google.com>:

    Internal change

251906769  by hongkuny<hongkuny@google.com>:

    Internal change

251303452  by haoyuzhang<haoyuzhang@google.com>:

    Internal change

PiperOrigin-RevId: 259442882

* Update ncf_keras_main.py