[llvm] Revert "[CodeGen] Use OwningArrayRef in NodeMetadata (NFC)" (PR #137684)

[Florian Mayer via llvm-commits]

fmayer wrote:

```
==llc==372806==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x55555a77cb4d in unsigned int* std::__1::__find[abi:nn210000]<unsigned int*, unsigned int*, int, std::__1::__identity>(unsigned int*, unsigned int*, int const&, std::__1::__identity&) /home/b/sanitizer-x86_64-linux-fast/build/libcxx_install_msan/include/c++/v1/__algorithm/find.h:49:41
    #1 0x55555a77caf4 in unsigned int* std::__1::find[abi:nn210000]<unsigned int*, int>(unsigned int*, unsigned int*, int const&) /home/b/sanitizer-x86_64-linux-fast/build/libcxx_install_msan/include/c++/v1/__algorithm/find.h:177:16
    #2 0x55555a77ca94 in bool llvm::is_contained<llvm::OwningArrayRef<unsigned int> const&, int>(llvm::OwningArrayRef<unsigned int> const&, int const&) /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/ADT/STLExtras.h:1914:12
    #3 0x55555a77ba3c in llvm::PBQP::RegAlloc::NodeMetadata::isConservativelyAllocatable() const /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/CodeGen/RegAllocPBQP.h:243:12
    #4 0x55555d22361d in llvm::PBQP::RegAlloc::RegAllocSolverImpl::setup() /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/CodeGen/RegAllocPBQP.h:409:39
    #5 0x55555d2231db in llvm::PBQP::RegAlloc::RegAllocSolverImpl::solve() /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/CodeGen/RegAllocPBQP.h:289:5
    #6 0x55555d214e03 in llvm::PBQP::RegAlloc::solve(llvm::PBQP::RegAlloc::PBQPRAGraph&) /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/include/llvm/CodeGen/RegAllocPBQP.h:518:25
    #7 0x55555d213fc9 in (anonymous namespace)::RegAllocPBQP::runOnMachineFunction(llvm::MachineFunction&) /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/RegAllocPBQP.cpp:873:33
    #8 0x55555cf32872 in llvm::MachineFunctionPass::runOnFunction(llvm::Function&) /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/CodeGen/MachineFunctionPass.cpp:108:10
    #9 0x55555d622cbc in llvm::FPPassManager::runOnFunction(llvm::Function&) /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1406:27
    #10 0x55555d62af5d in llvm::FPPassManager::runOnModule(llvm::Module&) /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1452:16
    #11 0x55555d6235f6 in runOnModule /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:1521:27
    #12 0x55555d6235f6 in llvm::legacy::PassManagerImpl::run(llvm::Module&) /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/lib/IR/LegacyPassManager.cpp:539:44
    #13 0x55555a1f3750 in compileModule /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:753:8
    #14 0x55555a1f3750 in main /home/b/sanitizer-x86_64-linux-fast/build/llvm-project/llvm/tools/llc/llc.cpp:400:22
    #15 0x7ffff7a2a3b7  (/lib/x86_64-linux-gnu/libc.so.6+0x2a3b7) (BuildId: 91f01b4ad171c80b6303d08d1f08cba8b990413d)
    #16 0x7ffff7a2a47a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2a47a) (BuildId: 91f01b4ad171c80b6303d08d1f08cba8b990413d)
    #17 0x55555a1525a4 in _start (/home/b/sanitizer-x86_64-linux-fast/build/llvm_build_msan/bin/llc+0x4bfe5a4)
```

https://github.com/llvm/llvm-project/pull/137684