[llvm] [VPlan] Run narrowInterleaveGroups during general VPlan optimizations. (PR #149706)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Thanks for the comments, I finally had some time to revisit the change. I recommitted the change as 6f253e87ddac3c3fffd71c6c5ccfa457096bc191 with the comments applied. I will take care of the independent changes separately.

https://github.com/llvm/llvm-project/pull/149706