message: test: Remove UninterruptibleSleep from test and replace it by SyncWithValidationInterfaceQueue
  For the purpose of this test the two have the same outcome, but this one
  is shorter and avoids a sleep for 0.1 seconds.
diff: @@ -207,9 +207,7 @@ BOOST_AUTO_TEST_CASE(processnewblock_signals_ordering)
  for (auto& t : threads) {
  t.join();
  }
  - while (GetMainSignals().CallbacksPending() > 0) {
  - UninterruptibleSleep(std::chrono::milliseconds{100});
  - }
  + SyncWithValidationInterfaceQueue();
  UnregisterSharedValidationInterface(sub);
  