Change flaky explain test to non-explain

This test's output changes depending on which worker is
picked for explain (e.g., worker port in the output changes).

Given that the test is only aiming to ensure that CTEs inside
CTEs work fine in DML queries, it should be fine to get rid of
the EXPLAIN. The output is verified to be correct as well.

src/test/regress/expected/dml_recursive.out

@@ -295,8 +295,7 @@ DEBUG:  common table expressions are not supported in distributed modifications
 DEBUG:  generating subplan 20_1 for CTE cte_1: WITH cte_2 AS (SELECT second_distributed_table.tenant_id AS cte2_id FROM recursive_dml_queries.second_distributed_table WHERE (second_distributed_table.dept OPERATOR(pg_catalog.>=) 2)) UPDATE recursive_dml_queries.distributed_table SET dept = 10 RETURNING tenant_id, dept, info
 DEBUG:  common table expressions are not supported in distributed modifications
 DEBUG:  Plan 20 query after replacing subqueries and CTEs: UPDATE recursive_dml_queries.distributed_table SET dept = 5 FROM (SELECT intermediate_result.tenant_id, intermediate_result.dept, intermediate_result.info FROM read_intermediate_result('20_1'::text, 'binary'::citus_copy_format) intermediate_result(tenant_id text, dept integer, info jsonb)) cte_1 WHERE (distributed_table.tenant_id OPERATOR(pg_catalog.<) cte_1.tenant_id)
-SET citus.explain_all_tasks TO ON;
+WITH cte_1 AS (
-EXPLAIN (COSTS FALSE) WITH cte_1 AS (
     WITH cte_2 AS (
         SELECT tenant_id as cte2_id 
         FROM second_distributed_table 
@@ -315,65 +314,6 @@ DEBUG:  common table expressions are not supported in distributed modifications
 DEBUG:  generating subplan 22_1 for CTE cte_1: WITH cte_2 AS (SELECT second_distributed_table.tenant_id AS cte2_id FROM recursive_dml_queries.second_distributed_table WHERE (second_distributed_table.dept OPERATOR(pg_catalog.>=) 2)) UPDATE recursive_dml_queries.distributed_table SET dept = 10 RETURNING tenant_id, dept, info
 DEBUG:  common table expressions are not supported in distributed modifications
 DEBUG:  Plan 22 query after replacing subqueries and CTEs: UPDATE recursive_dml_queries.distributed_table SET dept = 5 FROM (SELECT intermediate_result.tenant_id, intermediate_result.dept, intermediate_result.info FROM read_intermediate_result('22_1'::text, 'binary'::citus_copy_format) intermediate_result(tenant_id text, dept integer, info jsonb)) cte_1 WHERE (distributed_table.tenant_id OPERATOR(pg_catalog.<) cte_1.tenant_id)
-                                           QUERY PLAN                                           
-------------------------------------------------------------------------------------------------
- Custom Scan (Citus Router)
-   ->  Distributed Subplan 22_1
-         ->  Custom Scan (Citus Router)
-               Task Count: 4
-               Tasks Shown: All
-               ->  Task
-                     Node: host=localhost port=57638 dbname=regression
-                     ->  Update on distributed_table_2370000 distributed_table
-                           ->  Seq Scan on distributed_table_2370000 distributed_table
-               ->  Task
-                     Node: host=localhost port=57637 dbname=regression
-                     ->  Update on distributed_table_2370001 distributed_table
-                           ->  Seq Scan on distributed_table_2370001 distributed_table
-               ->  Task
-                     Node: host=localhost port=57638 dbname=regression
-                     ->  Update on distributed_table_2370002 distributed_table
-                           ->  Seq Scan on distributed_table_2370002 distributed_table
-               ->  Task
-                     Node: host=localhost port=57637 dbname=regression
-                     ->  Update on distributed_table_2370003 distributed_table
-                           ->  Seq Scan on distributed_table_2370003 distributed_table
-   Task Count: 4
-   Tasks Shown: All
-   ->  Task
-         Node: host=localhost port=57638 dbname=regression
-         ->  Update on distributed_table_2370000 distributed_table
-               ->  Nested Loop
-                     Join Filter: (distributed_table.tenant_id < intermediate_result.tenant_id)
-                     ->  Function Scan on read_intermediate_result intermediate_result
-                     ->  Materialize
-                           ->  Seq Scan on distributed_table_2370000 distributed_table
-   ->  Task
-         Node: host=localhost port=57637 dbname=regression
-         ->  Update on distributed_table_2370001 distributed_table
-               ->  Nested Loop
-                     Join Filter: (distributed_table.tenant_id < intermediate_result.tenant_id)
-                     ->  Function Scan on read_intermediate_result intermediate_result
-                     ->  Materialize
-                           ->  Seq Scan on distributed_table_2370001 distributed_table
-   ->  Task
-         Node: host=localhost port=57638 dbname=regression
-         ->  Update on distributed_table_2370002 distributed_table
-               ->  Nested Loop
-                     Join Filter: (distributed_table.tenant_id < intermediate_result.tenant_id)
-                     ->  Function Scan on read_intermediate_result intermediate_result
-                     ->  Materialize
-                           ->  Seq Scan on distributed_table_2370002 distributed_table
-   ->  Task
-         Node: host=localhost port=57637 dbname=regression
-         ->  Update on distributed_table_2370003 distributed_table
-               ->  Nested Loop
-                     Join Filter: (distributed_table.tenant_id < intermediate_result.tenant_id)
-                     ->  Function Scan on read_intermediate_result intermediate_result
-                     ->  Materialize
-                           ->  Seq Scan on distributed_table_2370003 distributed_table
-(55 rows)
-
 -- we don't support updating local table with a join with
 -- distributed tables
 UPDATE 

src/test/regress/sql/dml_recursive.sql

@@ -234,8 +234,7 @@ SET dept = 5
 FROM cte_1
 WHERE distributed_table.tenant_id < cte_1.tenant_id;
 
-SET citus.explain_all_tasks TO ON;
+WITH cte_1 AS (
-EXPLAIN (COSTS FALSE) WITH cte_1 AS (
     WITH cte_2 AS (
         SELECT tenant_id as cte2_id 
         FROM second_distributed_table