disable concat nested namespace check (#49571)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49571
Disable nested namespace check since OSS standard is
```
set(CMAKE_CXX_STANDARD 14)
```
and its currently causing confusion on clang-tidy internally such as D25214452
Test Plan: clang-tidy
Reviewed By: xuzhao9
Differential Revision: D25626392
fbshipit-source-id: 1fb472c89ebe9b83718ae27f2c1d77b8b2412b5e
Author
Rong Rong (AI Infra)
