[llvm] [VectorCombine] Use TCK_CodeSize for size-optimized functions (PR #202207)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon requested changes to this pull request.

CC @davemgreen I'm not certain how well other targets cost models handle different CostKinds

https://github.com/llvm/llvm-project/pull/202207