[llvm] [AArch64] Enable "sink-and-fold" in MachineSink by default (PR #67432)

[via llvm-commits]

bgra8 wrote:

@momchil-velikov as I reduce the file even further I get to less and less of a visible slow-down between this and previous compiler, so I had to stop the process as it was taking a lot of time.

With the attached reduced repro the slowdown is now 5x. I hope you find the issue. Please let me know if you need more info.

[repro.cc.zip](https://github.com/llvm/llvm-project/files/13196216/repro.cc.zip)


https://github.com/llvm/llvm-project/pull/67432