Removed unneeded code [skip ci]

Author: ankane

examples/citus/example.py

@@ -40,9 +40,6 @@
     for i in range(rows):
         copy.write_row([embeddings[i], categories[i]])
 
-        while conn.pgconn.flush() == 1:
-            pass
-
 print('Creating index in parallel')
 conn.execute('CREATE INDEX ON items USING hnsw (embedding vector_l2_ops)')