[llvm] [AArch64][LoopVectorize] Enable tail-folding on neoverse-v2 (PR #135357)

[Cullen Rhodes via llvm-commits]

c-rhodes wrote:

> I thought we decided not to do this because it was bad for performance in too many cases?

I wasn't aware this had been looked at previously, apologies. I see no regressions in spec2017 (int + fp), but will do some further benchmarking to make sure.

https://github.com/llvm/llvm-project/pull/135357