Clean up objects created by tests for index ordering check

These tests have been introduced in 23cabaf, but forgot to clean up
the objects created.  These are not required in any follow-up code
paths.

Backpatch-through: 15

expected/pg_hint_plan.out

@@ -4509,6 +4509,7 @@ error hint:
          Filter: (b = '''x'''::tsvector)
 (5 rows)
 
+DROP TABLE ischk;
 -- quote test
 /*+SeqScan("""t1 )	")IndexScan("t	2 """)HashJoin("""t1 )	"T3"t	2 """)Leading("""t1 )	"T3"t	2 """)Set(application_name"a	a	a""	a	A")*/
 EXPLAIN (COSTS false) SELECT * FROM t1 """t1 )	", t2 "t	2 """, t3 "T3" WHERE """t1 )	".id = "t	2 """.id AND """t1 )	".id = "T3".id;

sql/pg_hint_plan.sql

@@ -490,6 +490,7 @@ CREATE TABLE ischk_d2 PARTITION OF ischk FOR VALUES IN (1);
 CREATE INDEX ischk_idx ON ischk USING gin (b);
 /*+ IndexScan(ischk ischk_idx) */
 EXPLAIN (COSTS false) SELECT * FROM ischk WHERE b = 'x';
+DROP TABLE ischk;
 
 -- quote test
 /*+SeqScan("""t1 )	")IndexScan("t	2 """)HashJoin("""t1 )	"T3"t	2 """)Leading("""t1 )	"T3"t	2 """)Set(application_name"a	a	a""	a	A")*/