void decrementDeleted(String host, int port) {
    deletionHelper.decrementCount(host, port);
  }
Nullifies the delete notification on {@code host}:{@code port}.
This method is NOT thread safe and should not be used concurrently with other methods in this class like
await() and track().
@param host the host that to decrement on
@param port the port of the host that describes the instance along with {@code host}.
ambry-test-utils/src/main/java/com/github/ambry/server/MockCluster.java