Add a test for max_threads optimization for simple queries

tests/queries/0_stateless/01283_max_threads_simple_query_optimization.sql

@@ -0,0 +1,21 @@
+DROP TABLE IF EXISTS data_01283;
+
+CREATE TABLE data_01283 engine=MergeTree()
+ORDER BY key
+PARTITION BY key
+AS SELECT number key FROM numbers(10);
+
+SET log_queries=1;
+SELECT * FROM data_01283 LIMIT 1 FORMAT Null;
+SET log_queries=0;
+SYSTEM FLUSH LOGS;
+
+-- 1 for PullingAsyncPipelineExecutor::pull
+-- 1 for AsynchronousBlockInputStream
+SELECT
+    throwIf(count() != 1, 'no query was logged'),
+    throwIf(length(thread_ids) != 2, 'too many threads used')
+FROM system.query_log
+WHERE type = 'QueryFinish' AND query LIKE '%data_01283 LIMIT 1%'
+GROUP BY thread_ids
+FORMAT Null;