fix clang-tidy (#18030)

fix clang-tidy (#18030)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18030
ghimport-source-id: d68781226eee923c90be862ef54693feef5f1c1a

Stack:
* **#18030 [jit] fix clang-tidy**

fix the following complaint
```
pytorch/torch/csrc/jit/ir.cpp:84:7: error: pass by value and use std::move [modernize-pass-by-value,-warnings-as-errors]
      const std::string& delim = ", ")
      ^~~~~~~~~~~~~~~~~~
      std::string
```

Reviewed By: shannonzhu

Differential Revision: D14466714

fbshipit-source-id: 195cba335ae656db28fc6230b9e56ad208c88c29