In #47424 the readability-identifier-naming had been disabled for
clang-tidy builds, but the code base is already uses this notations, so
at least, let's enable it for clangd, so that developers who are using
editor/IDE with clangd will be warned.
FWIW clangd does not think that this check is slow [1], but I guess this
file hadn't been updated for quite a while.
[1]: https://github.com/llvm/llvm-project/blob/main/clang-tools-extra/clangd/TidyFastChecks.inc
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>