[VPlan] Prevent uses of materialized VPSymbolicValues. (NFC)#182318

fhahn merged 6 commits intollvm:mainllvm/llvm-project:mainfrom

fhahn:vplan-prevent-use-of-vpsymbolicvalue-after-matfhahn/llvm-project:vplan-prevent-use-of-vpsymbolicvalue-after-matCopy head branch name to clipboard