[llvm] [X86] Remove TuningFastVariableCrossLaneShuffle from X86_64V4Tuning (PR #212178)

[Phoebe Wang via llvm-commits]

phoebewang wrote:

Sorry, I mean I dropped the tuning from IceLakeServer and see regressions one more than improvements. So I think the change won't benefit Icelake server and early targets.

https://github.com/llvm/llvm-project/pull/212178