[clang-tidy] Fix fix-it overlaps in readability-static-definition-in-anonymous-namespace (#86599)

Because check emitted multiple warnings for every template instance
fix-it couldn't be applied due to overlaps.

Using TK_IgnoreUnlessSpelledInSource and restricting check to C++ only.

GitOrigin-RevId: 313734795c67ca0bfb82f96b39e123774ddf24b4
3 files changed