[llvm] [NFC][AArch64] Refactor Arm llvm-mca tests (PR #183294)

[Nashe Mncube via llvm-commits]

nasherm wrote:

> Can the files in llvm/test/tools/llvm-mca/AArch64/Apple/Inputs/ be removed too?
> 
> What is your plan for the new tests for C1-Ultra? I don't think we should have a C1 directory, that doesn't really group anything in a meaningful way. You could just put them in Cortex though, or the top level directory.

Sure. I'll just place the C1-Ultra tests into Cortex

https://github.com/llvm/llvm-project/pull/183294