tests: add sorted result for a test (#47415)

close pingcap/tidb#47411

tests/integrationtest/t/planner/core/integration.test

@@ -1906,6 +1906,7 @@ explain select rank() over (partition by table_name) from information_schema.tab
 drop table if exists t;
 create table deci (a decimal(65,30),b decimal(65,0));
 insert into deci values (1234567890.123456789012345678901234567890,987654321098765432109876543210987654321098765432109876543210);
+--sorted_result
 select a from deci union ALL select b from deci;