Revert "[lli] Revisit Orc debug output tests" (#79055)

Reverts llvm/llvm-project#76822

This fails to build with gcc 7.5:
```
llvm/tools/lli/lli.cpp:1087:16: error: could not convert ‘Obj’ from ‘std::unique_ptr<llvm::MemoryBuffer>’ to ‘llvm::Expected<std::unique_ptr<llvm::MemoryBuffer> >’
         return Obj;
                ^~~
```