fix test

Author: nickitat

tests/queries/0_stateless/03405_merge_filter_into_join.sql

@@ -9,6 +9,7 @@ INSERT INTO users VALUES (8888, 'Alice', 50);
 set query_plan_join_swap_table = 0;
 set enable_analyzer = 1; -- Optimization requires LogicalJoinStep
 set enable_parallel_replicas = 0; -- Optimization requires LogicalJoinStep
+set parallel_hash_join_threshold = 0;
 
 -- { echoOn }