Core ML Has Added `Index_Put` Support, No Need to Skip Anymore (#2975)

Summary:
It was a workaround to skip `aten.index_put` op in Core ML delegation, at the cost of partitioning the Llama model into 13 pieces.

For better performance, we prefer to delegate the whole model to Core ML. Since Core ML has added the [necessary support](https://github.com/apple/coremltools/pull/2190), it is time to revert this workaround

Pull Request resolved: https://github.com/pytorch/executorch/pull/2975

Reviewed By: kirklandsign

Differential Revision: D56002979

Pulled By: cccclai

fbshipit-source-id: e7a7c8c43706cb57eba3e6f720b3d713bec5065b