KAFKA-16988: add 1 more node for test_exactly_once_source system test (#16379)


Reviewers: Igor Soarez <soarez@apple.com>
diff --git a/tests/kafkatest/tests/connect/connect_distributed_test.py b/tests/kafkatest/tests/connect/connect_distributed_test.py
index 1e60545..a244d7e 100644
--- a/tests/kafkatest/tests/connect/connect_distributed_test.py
+++ b/tests/kafkatest/tests/connect/connect_distributed_test.py
@@ -822,7 +822,7 @@
 
         assert success, "Found validation errors:\n" + "\n  ".join(errors)
 
-    @cluster(num_nodes=6)
+    @cluster(num_nodes=7)
     @matrix(
         clean=[True, False],
         connect_protocol=['sessioned', 'compatible', 'eager'],