[llvm] [VPlan] Fold common edges away in convertPhisToBlends (PR #150368)

[Florian Hahn via llvm-commits]

fhahn wrote:

I am not sure removing blends completely is desireable, as more abstract recipes help to keep things simple early on.

Better to move this first into simplifyBlends. 

https://github.com/llvm/llvm-project/pull/150368