KafkaAdminClient#timeoutCallsInFlight does not work as expected

KafkaAdminClient#timeoutCallsInFlight does not work as expected. The original idea was that this function would time out a call by closing the associated socket. Then the following NetworkClient#poll call would trigger the call to be removed. However, it turns out that it sometimes takes time for the NetworkClient#poll call to return the disconnection events. This leads to the call lingering for a while, causing us to repeatedly disconnect connections to that node.