Fix concurrent modification error in AuctionMark

[nuno-faria]

In the updateItemQueues function, the code iterates each item queue and calls the addItemToProperQueue for each item. One step this function does is remove the item from the original list, if the new status is different from the old one.
This, however, triggers a ConcurrentModificationException exception since we are iterating and removing concurrently from the linked list:

java.util.ConcurrentModificationException
	at java.base/java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:970)
	at java.base/java.util.LinkedList$ListItr.next(LinkedList.java:892)
	at com.oltpbenchmark.benchmarks.auctionmark.AuctionMarkProfile.updateItemQueues(AuctionMarkProfile.java:749)
	at com.oltpbenchmark.benchmarks.auctionmark.AuctionMarkWorker.executeCloseAuctions(AuctionMarkWorker.java:454)
	at com.oltpbenchmark.benchmarks.auctionmark.AuctionMarkWorker.executeWork(AuctionMarkWorker.java:350)
	at com.oltpbenchmark.api.Worker.doWork(Worker.java:416)
	at com.oltpbenchmark.api.Worker.run(Worker.java:282)
	at java.base/java.lang.Thread.run(Thread.java:833)

The proposed solution passes a reference to the iterator in the updateItemQueues function, so the addItemToProperQueue can safely remove the element using iterator.remove(). This also means that the code in the addItemToProperQueue function does not need to iterate over the entire list again by calling remove, improving performance. The other functions that call updateItemQueues seem to be always new items, so we can set the iterator as null as they don't need to remove from an existing queue.

[apavlo]

LGTM