Tracking issue for the follow up comments in #22904. It seems that PR has introduced lock contentions, and/or the `checkqueue_tests` are now behaving very poorly, with long runtimes and generating GBs of log output in some cases. See comments starting here: https://github.com/bitcoin/bitcoin/pull/22904#issuecomment-930466935.

cc @ajtowns @theuni @martinus  
{
        return true;
    }
    void swap(FakeCheck& x){};
};
struct FakeCheckCheckCompletion {
    static std::atomic<size_t> n_calls;
    bool operator()()
    {
        n_calls.fetch_add(1, std::memory_order_relaxed);
        return true;
    }
    void swap(FakeCheckCheckCompletion& x){};
};
struct FailingCheck {
    bool fails;
    FailingCheck(bool _fails) : fails(_fails){};
    FailingCheck() : fails(true){};
    bool operator()() const