Reduce queue polling time in ProcessingIterator

Updated ProcessingIterator's queue polling from one second to 50 milliseconds for improved performance. This facilitates faster document processing across more cores, reducing bottlenecks and slow single-threaded processing.

code/libraries/blocking-thread-pool/src/main/java/nu/marginalia/util/ProcessingIterator.java

@@ -75,7 +75,7 @@ public class ProcessingIterator<T> implements Iterator<T> {
             return true;
 
         do {
-            next = queue.poll(1, TimeUnit.SECONDS);
+            next = queue.poll(50, TimeUnit.MILLISECONDS);
             if (next != null) {
                 return true;
             }