[decomp] Remove pixel_shuffle from core aten decomps (#118921)
pixel_shuffle is a core aten op
(https://pytorch.org/docs/main/torch.compiler_ir.html#core-aten-ir) so we should not decompose it.
https://github.com/pytorch/pytorch/pull/118239 added a decomp for it which is causing an internal test failure
(https://www.internalfb.com/intern/test/281475090561210/) which cases on the pixel_shuffle operator.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/118921
Approved by: https://github.com/SherlockNoMad, https://github.com/lezcano
