[llvm] [VPlan] Introduce all loop regions as VPlan transform. (NFC) (PR #129402)

[Florian Hahn via llvm-commits]

fhahn wrote:

> "Introduce all loop regions as VPlan transform" may be a more accurate title than "Introduce child regions as VPlan transform."

Thanks, updated! Also added NFC, as it only changes minor debug output

https://github.com/llvm/llvm-project/pull/129402