[NFC][CLANG] Fix static analyzer bugs about unnecessary object copies with auto keyword (#75082)

Reported by Static Analyzer Tool:

In ​EmitAssemblyHelper::​RunOptimizationPipeline(): Using the auto
keyword without an & causes the copy of an object of type function.

 /// List of pass builder callbacks ("CodeGenOptions.h").
std::vector<std::function<void(llvm::PassBuilder &)>>
PassBuilderCallbacks;