[msan][NFC] Add arm64-vmax.ll tests (#129760)

Forked from llvm/test/CodeGen/AArch64/arm64-vmax.ll

Pairwise instructions which are handled incorrectly by heuristics:
- llvm.aarch64.neon.fmaxp (floating-point maximum pairwise)
- llvm.aarch64.neon.fminp
- llvm.aarch64.neon.fmaxnmp (floating-point maximum number pairwise)
- llvm.aarch64.neon.fminnmp
- llvm.aarch64.neon.smaxp
- llvm.aarch64.neon.sminp
- llvm.aarch64.neon.umaxp
- llvm.aarch64.neon.uminp
Future work should consider whether handlePairwiseShadowOrIntrinsic is a
more appropriate handler.

Other instructions which are handled correctly by heuristics:
- llvm.aarch64.neon.fmax
- llvm.aarch64.neon.fmin
- llvm.aarch64.neon.smax
- llvm.aarch64.neon.smin
- llvm.aarch64.neon.umax
- llvm.aarch64.neon.umin

Author: thurstond