Remove dangling stderr print

Author: amarziali

dd-java-agent/instrumentation/ignite-2.0/src/main/java/datadog/trace/instrumentation/ignite/v2/cache/SpanFinishingCallback.java

@@ -20,9 +20,7 @@ public SpanFinishingCallback(final AgentSpan span) {
   @Override
   public void apply(IgniteFuture<?> igniteFuture) {
     IgniteCacheDecorator.DECORATE.beforeFinish(span);
-
-    System.err.println("Called callback: " + igniteFuture);
-
+    
     try {
       Object result = igniteFuture.get();
       IgniteCacheDecorator.DECORATE.beforeFinish(span);