message: cleanup: fix words in assertion message.
diff: @@ -482,7 +482,7 @@ FakeUpstream::waitForHttpConnection(Event::Dispatcher& client_dispatcher,
  std::vector<std::unique_ptr<FakeUpstream>>& upstreams,
  FakeHttpConnectionPtr& connection, milliseconds timeout) {
  if (upstreams.empty()) {
  - return AssertionFailure() << "No upstreams confgured.";
  + return AssertionFailure() << "No upstreams configured.";
  }
  Event::TestTimeSystem& time_system = upstreams[0]->timeSystem();
  auto end_time = time_system.monotonicTime() + timeout;
  