[llvm] [VPlan] Unroll VPReplicateRecipe by VF. (PR #142433)

[Steve Scalpone via llvm-commits]

sscalpone wrote:

Seeing similar.
```
clang -c -march=haswell -O2  reduced.ll
```
[reduced.ll.gz](https://github.com/user-attachments/files/20962299/reduced.ll.gz)

```
.../llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp:2758: virtual void llvm::VPReplicateRecipe::execute(llvm::VPTransformState&): Assertion `IsSingleScalar && "VPReplicateRecipes outside replicate regions " "must have already been unrolled"' failed.
```

https://github.com/llvm/llvm-project/pull/142433