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  
#include <checkqueue.h>
#include <sync.h>
#include <test/util/setup_common.h>
#include <util/system.h>
#include <util/time.h>
#include <boost/test/unit_test.hpp>
#include <atomic>
#include <condition_variable>
#include <mutex>
#include <thread>
#include <unordered_set>
#include <utility>
#include <vector>
BOOST_FIXTURE_TEST_SUITE(checkqueue_tests, TestingSetup)
static const unsigned int QUEUE_BATCH_SIZE = 128;
static const int SCRIPT_CHECK_THREADS = 3;
struct FakeCheck {
    bool operator()() const