MINOR: remove System.out in test (#20494)

This PR removes two System.out.println(...) statements from
StreamsGraphTest. These outputs were left over from debugging and are
not needed in the test logic.

Reviewers: Ken Huang <[email protected]>, TengYao Chi
 <[email protected]>, Chia-Ping Tsai <[email protected]>

Author: mjsax

streams/src/test/java/org/apache/kafka/streams/kstream/internals/graph/StreamsGraphTest.java

@@ -192,8 +192,6 @@ public void shouldPartiallyOptimizeWithValueOrKeyChangingOperatorsAfterInitialKe
         final Topology attemptedOptimize = getTopologyWithChangingValuesAfterChangingKey(StreamsConfig.OPTIMIZE, false);
         final Topology noOptimization = getTopologyWithChangingValuesAfterChangingKey(StreamsConfig.NO_OPTIMIZATION, false);
 
-        System.out.println(attemptedOptimize.describe().toString());
-        System.out.println(noOptimization.describe().toString());
         assertEquals("Topologies:\n" +
                 "   Sub-topology: 0\n" +
                 "    Source: KSTREAM-SOURCE-0000000000 (topics: [input])\n" +