Added stage id to JSON plan (#2420)

.github/config/muted_ya.txt

@@ -12,7 +12,6 @@ ydb/core/kqp/provider/ut KikimrIcGateway.TestLoadBasicSecretValueFromExternalDat
 ydb/core/kqp/ut/federated_query/generic *
 ydb/core/kqp/ut/olap *
 ydb/core/kqp/ut/pg KqpPg.CreateIndex
-ydb/core/kqp/ut/pg KqpPg.Returning
 ydb/core/kqp/ut/query KqpLimits.QueryReplySize
 ydb/core/kqp/ut/query KqpQuery.QueryTimeout
 ydb/core/kqp/ut/scan KqpRequestContext.TraceIdInErrorMessage

ydb/core/kqp/opt/kqp_query_plan.cpp

@@ -883,7 +883,7 @@ private:
                 auto& cteNode = AddPlanNode(QueryPlanNodes.begin()->second);
                 cteNode.Plans.insert(stageId);
                 cteNode.TypeName = TStringBuilder() << commonNode.TypeName;
-                cteNode.CteName = cteNode.TypeName;
+                cteNode.CteName = TStringBuilder() << cteNode.TypeName << "_" << stageId;
 
                 parentNode.CteRefName = *cteNode.CteName;
                 planNode.CteRefName = *cteNode.CteName;