[llvm] [MachinePipeliner] Fix fragile tests (PR #123169)

[Sumanth Gundapaneni via llvm-commits]

sgundapa wrote:

@iajbar @quic-santdas - you should evaluate the impact of the associated patches on HVX kernels, specificially if it is known that the II is changing.  Or probably provide a way for the author of this patch to run these benchmarks. 

https://github.com/llvm/llvm-project/pull/123169