More compact format for worker logs (#4092)

test/runtest.py

@@ -2535,10 +2535,10 @@ def test_logging_to_driver(shutdown_only):
         time.sleep(1)
 
     output_lines = captured["out"]
-    assert len(output_lines) == 0
-    error_lines = captured["err"]
     for i in range(200):
-        assert str(i) in error_lines
+        assert str(i) in output_lines
+    error_lines = captured["err"]
+    assert len(error_lines) == 0
 
 
 def test_not_logging_to_driver(shutdown_only):