Remove useless output from EXPLAIN

Before the change, EXPLAIN would print "Cost: ?, Output: ? rows (?B)"
for every node. This information is available only in EXPLAIN ANALYZE.

Extracted-From: trinodb/trino@ce9ecf9

presto-main/src/main/java/com/facebook/presto/sql/planner/planPrinter/TextRenderer.java

@@ -100,7 +100,7 @@ private String printStats(PlanRepresentation plan, NodeRepresentation node)
     {
         StringBuilder output = new StringBuilder();
         if (!node.getStats().isPresent() || !(plan.getTotalCpuTime().isPresent() && plan.getTotalScheduledTime().isPresent())) {
-            return "Cost: ?, Output: ? rows (?B)\n";
+            return "";
         }
 
         PlanNodeStats nodeStats = node.getStats().get();