[KIKIMR-21472] Output the final AST in explain query (ydb-platform#6487)

(cherry picked from commit 85d4495)

Author: abyss7

ydb/core/kqp/host/kqp_explain_prepared.cpp

@@ -66,7 +66,7 @@ class TKqpExplainPreparedTransformer : public NYql::TGraphTransformerBase {
 
         PhyQuerySetTxPlans(query, TKqpPhysicalQuery(TransformCtx->ExplainTransformerInput), std::move(TxResults),
             ctx, Cluster, TransformCtx->Tables, TransformCtx->Config, TypeCtx, OptimizeCtx);
-        query.SetQueryAst(KqpExprToPrettyString(*TransformCtx->ExplainTransformerInput, ctx));
+        query.SetQueryAst(KqpExprToPrettyString(*input, ctx));
 
         TransformCtx->ExplainTransformerInput = nullptr;
         return TStatus::Ok;

ydb/core/kqp/ut/olap/helpers/aggregation.h

@@ -81,12 +81,7 @@ class TAggregationTestCase {
     bool UseLlvm = true;
 public:
     void FillExpectedAggregationGroupByPlanOptions() {
-#if SSA_RUNTIME_VERSION >= 2U
-        //            AddExpectedPlanOptions("TKqpOlapAgg");
         AddExpectedPlanOptions("WideCombiner");
-#else
-        AddExpectedPlanOptions("CombineCore");
-#endif
     }
     TString GetFixedQuery() const {
         TStringBuilder queryFixed;
@@ -177,7 +172,8 @@ void CheckPlanForAggregatePushdown(
     const TString& query,
     TClient& client,
     const std::vector<std::string>& expectedPlanNodes,
-    const std::string& readNodeType) {
+    const std::string& readNodeType)
+{
     auto res = StreamExplainQuery(query, client);
     UNIT_ASSERT_C(res.IsSuccess(), res.GetIssues().ToString());
 
@@ -242,4 +238,4 @@ void WriteTestDataForTableWithNulls(TKikimrRunner& kikimr, TString testTable);
 
 void TestTableWithNulls(const std::vector<TAggregationTestCase>& cases, const bool genericQuery = false);
 
-}
+}

ydb/core/kqp/ut/olap/kqp_olap_ut.cpp

@@ -2515,7 +2515,7 @@ Y_UNIT_TEST_SUITE(KqpOlap) {
         UNIT_ASSERT_C(result.GetStatus() == NYdb::EStatus::SUCCESS, result.GetIssues().ToString());
 
         auto client = kikimr.GetQueryClient();
-        { 
+        {
             auto prepareResult = client.ExecuteQuery(R"(
                 REPLACE INTO `/Root/ColumnShard` (a, b, c) VALUES
                     (1u, 1, 5),
@@ -2545,15 +2545,15 @@ Y_UNIT_TEST_SUITE(KqpOlap) {
                     UNIT_ASSERT_C(plan.QueryStats->Getquery_ast().Contains("return (FromFlow (NarrowMap (WideFromBlocks"), plan.QueryStats->Getquery_ast());
                     break;
                 case NKikimrConfig::TTableServiceConfig_EBlockChannelsMode_BLOCK_CHANNELS_AUTO:
-                    UNIT_ASSERT_C(plan.QueryStats->Getquery_ast().Contains("return (FromFlow (ExpandMap (NarrowMap (WideFromBlocks"), plan.QueryStats->Getquery_ast());
+                    UNIT_ASSERT_C(plan.QueryStats->Getquery_ast().Contains("return (FromFlow (WideFromBlocks"), plan.QueryStats->Getquery_ast());
                     break;
                 case NKikimrConfig::TTableServiceConfig_EBlockChannelsMode_BLOCK_CHANNELS_FORCE:
                     UNIT_ASSERT_C(plan.QueryStats->Getquery_ast().Contains("return (FromFlow (WideMap"), plan.QueryStats->Getquery_ast());
                     break;
             }
         }
 
-        { 
+        {
             auto it = client.StreamExecuteQuery(R"(
                 SELECT
                     b, COUNT(*), SUM(a)