[llvm] [FastISel][AArch64] Compare Instruction Miscompilation Fix (PR #75993)

[via llvm-commits]

brendaso1 wrote:

Added the generated CHECK lines to the unit tests. Let's see how the builders look.

Also, when I did more testing, it seems like the sample test wouldn't fail even if the Cmp is sign-extended rather than zero-extended in assembly. So I removed the related changes as well. 

https://github.com/llvm/llvm-project/pull/75993