Add new helper to erase dead instructions inserted during SCEV expansion but not being used due to InstSimplifyFolder simplifications. Together with https://github.com/llvm/llvm-project/pull/157307 this also allows removing some specialized folds, e.g. https://github.com/llvm/llvm-project/blob/main/llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp#L2205 PR: https://github.com/llvm/llvm-project/pull/157308