Fix random test failures

Probably broken as a result of PostgreSQL patches or maybe my
toolchain, I dunno. Throwing ORDER BY clauses in helps, as always.

src/test/regress/expected/multi_single_relation_subquery.out

@@ -95,7 +95,7 @@ from
 group by
     suppkey_bin
 order by
-    avg_count desc
+    avg_count desc, suppkey_bin DESC
 limit 20;
  suppkey_bin |     avg_count      
 -------------+--------------------

src/test/regress/expected/multi_subquery_in_where_clause.out

@@ -112,13 +112,13 @@ ORDER BY 1;
 FROM 
   users_table 
 WHERE 
-  user_id =ANY(SELECT user_id FROM users_table WHERE value_1 >= 10 AND value_1 <= 20) GROUP BY 1 ORDER BY 2 DESC LIMIT 5;
+  user_id =ANY(SELECT user_id FROM users_table WHERE value_1 >= 10 AND value_1 <= 20) GROUP BY 1 ORDER BY 2 DESC, 1 ASC LIMIT 5;
  user_id | count 
 ---------+-------
       12 |   121
       87 |   117
-      37 |   115
       23 |   115
+      37 |   115
       46 |   115
 (5 rows)
 

src/test/regress/sql/multi_single_relation_subquery.sql

@@ -74,7 +74,7 @@ from
 group by
     suppkey_bin
 order by
-    avg_count desc
+    avg_count desc, suppkey_bin DESC
 limit 20;
 
 select

src/test/regress/sql/multi_subquery_in_where_clause.sql

@@ -83,7 +83,7 @@ ORDER BY 1;
 FROM 
   users_table 
 WHERE 
-  user_id =ANY(SELECT user_id FROM users_table WHERE value_1 >= 10 AND value_1 <= 20) GROUP BY 1 ORDER BY 2 DESC LIMIT 5;
+  user_id =ANY(SELECT user_id FROM users_table WHERE value_1 >= 10 AND value_1 <= 20) GROUP BY 1 ORDER BY 2 DESC, 1 ASC LIMIT 5;
 
 -- users that appeared more than 118 times
 SELECT