Attempt to prevent the deadlock in the QueueDiskChannel Test again (#18415)

* Attempt to prevent the deadlock in the QueueDiskChannel Test again

This time we're going to adjust the pause tests to only test the right
flag.

* Only switch off pushback once we know that we are not pushing anything else
* Ensure full redirection occurs
* More nicely handle a closed datachan
* And handle similar problems in queue_channel_test

Signed-off-by: Andrew Thornton <art27@cantab.net>

modules/queue/queue_bytefifo.go

@@ -205,7 +205,10 @@ loop:
 				// tell the pool to shutdown.
 				q.baseCtxCancel()
 				return
-			case data := <-q.dataChan:
+			case data, ok := <-q.dataChan:
+				if !ok {
+					return
+				}
 				if err := q.PushBack(data); err != nil {
 					log.Error("Unable to push back data into queue %s", q.name)
 				}