[llvm] [LoopVectorize] Use CodeSize as the cost kind for minsize (PR #124119)

[John Brawn via llvm-commits]

john-brawn-arm wrote:

> I don't see anything aarch64 or arm-specific about these changes. Can the tests be moved to the parent folder?

Costs are calculated by TargetTransformInfo and so are target-dependent. The two test files are also expecting different things, e.g. in the dont_vectorize_with_minsize we expect different vectorization factors in arm and aarch64.

https://github.com/llvm/llvm-project/pull/124119