investigate timeout exception in eventhubs client during shutdown

We oftentimes see timeout when trying to shutdown consumer/producer because the EH client times out when closing. Need to investigate the root cause and fix it or push a fix in the EH client.

java.util.concurrent.TimeoutException java.util.concurrent.CompletableFuture.timedGet - Line 1771 (CompletableFuture.java) java.util.concurrent.CompletableFuture.get - Line 1915 (CompletableFuture.java) org.apache.samza.system.eventhub.consumer.EventHubSystemConsumer$1.run - Line 442 (EventHubSystemConsumer.java) java.util.concurrent.Executors$RunnableAdapter.call - Line 511 (Executors.java) java.util.concurrent.FutureTask.run - Line 266 (FutureTask.java) java.util.concurrent.ThreadPoolExecutor.runWorker - Line 1142 (ThreadPoolExecutor.java) java.util.concurrent.ThreadPoolExecutor$Worker.run - Line 617 (ThreadPoolExecutor.java) java.lang.Thread.run - Line 745 (Thread.java)