Returns number of flow output plugin log entries of a given flow.

def CountFlowOutputPluginLogEntries(self,
                                      client_id,
                                      flow_id,
                                      output_plugin_id,
                                      with_type=None):
    """Returns number of flow output plugin log entries of a given flow."""

    return len(
        self.ReadFlowOutputPluginLogEntries(
            client_id,
            flow_id,
            output_plugin_id,
            0,
            sys.maxsize,
            with_type=with_type))