Revert "[VPlan] Add & use VPValue operands for VPWidenRecipe (NFC)."
This reverts commit 9245c7ac13480ed48ae339ad0e68cbe680cd0642.
This is triggering a segfault in XLA downstream, we'll follow-up with
a reproducer, it is likely influenced by TTI/TLI settings or other
options as a simple opt -loop-vectorize invocation on the IR
before the crash does not reproduce immediately.