Show last iteration time rather than average

The average isn't very useful now since the small files at the start
throw it off and the estimated time is more important.

stages/02_flatten-openalex-jsonl.py

@@ -262,11 +262,12 @@ def flatten_authors():
             total_size_done += os.path.getsize(jsonl_file_name)
             if FILES_PER_ENTITY and files_done >= FILES_PER_ENTITY:
                 break
-            total_time += time.time() - start_time
+            iter_time = time.time() - start_time
+            total_time += iter_time
             avg_time = total_time / files_done
             avg_time_per_byte = total_time / total_size_done
             est_time = avg_time_per_byte * (total_size - total_size_done)
-            print(f"flatten_authors loop average time: {avg_time} seconds")
+            print(f"flatten_authors time: {iter_time} seconds")
             print(f"flatten_authors estimated time remaining: {est_time / 60} minutes")
 
     print(f"Flattening authors done in {total_time} seconds")
@@ -693,11 +694,12 @@ def flatten_works():
             total_size_done += os.path.getsize(jsonl_file_name)
             if FILES_PER_ENTITY and files_done >= FILES_PER_ENTITY:
                 break
-            total_time += time.time() - start_time
+            iter_time = time.time() - start_time
+            total_time += iter_time
             avg_time = total_time / files_done
             avg_time_per_byte = total_time / total_size_done
             est_time = avg_time_per_byte * (total_size - total_size_done)
-            print(f"flatten_works loop average time: {avg_time} seconds")
+            print(f"flatten_works time: {iter_time} seconds")
             print(f"flatten_works estimated time remaining: {est_time / 60} minutes")
 
     print(f"Flattening works done in {total_time} seconds")