[clang-tools-extra] [clang-tidy][NFC] Don't qualify names unless strictly necessary (PR #185169)

[via cfe-commits]

https://github.com/EugeneZelenko approved this pull request.

Were these changes made using #180404? If not, will be good idea to run new check separately to ensure that it catches same things (except `constexpr` and added namespaces), so it could be used in future to maintain code.

https://github.com/llvm/llvm-project/pull/185169