Fix use after free (#11239)

Author: Hor911

ydb/core/kqp/opt/kqp_query_plan.cpp

@@ -1458,10 +1458,10 @@ class TxPlanSerializer {
         op.Properties["Name"] = name;
         op.Properties["Condition"] = MakeJoinConditionString(join.LeftKeysColumnNames(), join.RightKeysColumnNames());
 
-        auto operatorId = AddOperator(planNode, name, std::move(op));
-
         AddOptimizerEstimates(op, join);
 
+        auto operatorId = AddOperator(planNode, name, std::move(op));
+
         Visit(flatMap, planNode);
 
         return operatorId;