[llvm] [IR] Simplify HasCachedHash with is_detected (NFC) (PR #159510)

[Justin Fargnoli via llvm-commits]

justinfargnoli wrote:

I'm seeing the following tests fail as a result of this commit:
```
Failed Tests (13):
  LLVM :: Analysis/TypeBasedAliasAnalysis/dse.ll
  LLVM :: DebugInfo/macro_link.ll
  LLVM :: Linker/unique-fwd-decl-a.ll
  LLVM :: Linker/unique-fwd-decl-order.ll
  LLVM :: Verifier/noalias_scope_decl.ll
  LLVM-Unit :: IR/./IRTests/GenericDINodeTest/get
  LLVM-Unit :: IR/./IRTests/IRBuilderTest/DIBuilderMacro
  LLVM-Unit :: IR/./IRTests/MDNodeTest/DistinctOnUniquingCollision
  LLVM-Unit :: IR/./IRTests/MDNodeTest/NullOperand
  LLVM-Unit :: IR/./IRTests/MDNodeTest/UniquedOnDeletedOperand
  LLVM-Unit :: IR/./IRTests/MDNodeTest/handleChangedOperandRecursion
  LLVM-Unit :: IR/./IRTests/MDNodeTest/replaceWithPermanent
  LLVM-Unit :: IR/./IRTests/MDNodeTest/replaceWithUniquedChangedOperand


Testing Time: 63.54s

Total Discovered Tests: 73695
  Skipped          :   649 (0.88%)
  Unsupported      : 48670 (66.04%)
  Passed           : 24264 (32.92%)
  Expectedly Failed:    99 (0.13%)
  Failed           :    13 (0.02%)
```

However, I haven't root caused this. (i.e. perhaps these failures can be attributed to a local change) 

For context, here's a subset of my build configuration:
```
    'cmake',
    '-G', 'Ninja',
    '-DCMAKE_BUILD_TYPE=Debug',
    '-DLLVM_ENABLE_ASSERTIONS=ON',
    '-Wno-dev',
    '-DLLVM_CCACHE_BUILD=ON',
    '-DLLVM_OPTIMIZED_TABLEGEN=ON',
    '-DLLVM_ENABLE_LLD=ON',
    '-DCMAKE_C_COMPILER=/usr/bin/clang-18',
    '-DCMAKE_CXX_COMPILER=/usr/bin/clang++-18',
    '-DBUILD_SHARED_LIBS=ON',
    '-DCMAKE_CUDA_COMPILER=/usr/local/cuda/bin/nvcc',
```

I have not tried building with `gcc` or any other C++ compiler. 

https://github.com/llvm/llvm-project/pull/159510