Restore TF embeddings and attention layers to their previous version
# What does this PR do?

This PR restores the attention layers and the embeddings as it was in v4.1, even though the embeddings got few improvements compared to their original version to keep XLA compliancy. The reason is because we realized that some used operators were not compatible with some NN SDKs such as the one from Qualcomm or ONNX.

Pinging @mfuntowicz <|||||>> Morgan was mentioning that the transpose_for_score method was called right after the Q/K/V projection, but that there was no need to split this dimension if we're not doing head masking.
What do you think? Maybe that's some work for another PR, though.

I think it seems doable but not sure, I prefer to keep things like this to be sure we revert properly as it was before and we get at least a proper version, and we can take care of this change in another PR.<|||||>Sounds good to me!<|||||>LGTM! @patrickvonplaten feel free to merge if you approve the changes ^^<|||||>I won't have time to do a proper review today (can do it tomorrow), but feel free to merge without me if @LysandreJik and @sgugger are ok with it<|||||>@patrickvonplaten if you can take a look at it today and merge it if it's fine with you, that would be great