infra/c++_tests cleanup: remove unnecessary includes
#include <atomic>
#include <cassert>
#include <cmath>
-#include <cstdint>
#include <cstdio>
#include <cstring>
#include <array>
#include <functional>
#include <limits>
-#include <string>
#include <iostream>
#include <sstream>
-#include <utility>
#include <gtest/gtest.h>
-#include "rust_interface/rust_tuple.h"
#include "rust_interface/CheckPrimitiveTypesClass.hpp"
#include "rust_interface/Foo.hpp"
#include "rust_interface/SomeObserver.hpp"
