PG18 - pg17.sql Simplify step 10 verification to use COUNT(*) instead of SELECT * (#8111)

fixes #8096 

PostgreSQL 18 adds a `conenforced` flag allowing `CHECK` constraints to
be declared `NOT ENFORCED`.



ca87c415e2
```diff
@@ -1256,26 +1278,26 @@
  distributed_partitioned_table_id_partition_col_excl | x
 (2 rows)
 
 -- Step 9: Drop the exclusion constraints from both tables
 \c - - :master_host :master_port
 SET search_path TO pg17;
 ALTER TABLE distributed_partitioned_table DROP CONSTRAINT dist_exclude_named;
 ALTER TABLE local_partitioned_table DROP CONSTRAINT local_exclude_named;
 -- Step 10: Verify the constraints were dropped
 SELECT * FROM pg_constraint WHERE conname = 'dist_exclude_named' AND contype = 'x';
- oid | conname | connamespace | contype | condeferrable | condeferred | convalidated | conrelid | contypid | conindid | conparentid | confrelid | confupdtype | confdeltype | confmatchtype | conislocal | coninhcount | connoinherit | conkey | confkey | conpfeqop | conppeqop | conffeqop | confdelsetcols | conexclop | conbin
+ oid | conname | connamespace | contype | condeferrable | condeferred | conenforced | convalidated | conrelid | contypid | conindid | conparentid | confrelid | confupdtype | confdeltype | confmatchtype | conislocal | coninhcount | connoinherit | conperiod | conkey | confkey | conpfeqop | conppeqop | conffeqop | confdelsetcols | conexclop | conbin 
 -----+---------+--------------+---------+---------------+-------------+-------------+--------------+----------+----------+----------+-------------+-----------+-------------+-------------+---------------+------------+-------------+--------------+-----------+--------+---------+-----------+-----------+-----------+----------------+-----------+--------
 (0 rows)
 
 SELECT * FROM pg_constraint WHERE conname = 'local_exclude_named' AND contype = 'x';
- oid | conname | connamespace | contype | condeferrable | condeferred | convalidated | conrelid | contypid | conindid | conparentid | confrelid | confupdtype | confdeltype | confmatchtype | conislocal | coninhcount | connoinherit | conkey | confkey | conpfeqop | conppeqop | conffeqop | confdelsetcols | conexclop | conbin
+ oid | conname | connamespace | contype | condeferrable | condeferred | conenforced | convalidated | conrelid | contypid | conindid | conparentid | confrelid | confupdtype | confdeltype | confmatchtype | conislocal | coninhcount | connoinherit | conperiod | conkey | confkey | conpfeqop | conppeqop | conffeqop | confdelsetcols | conexclop | conbin 
 -----+---------+--------------+---------+---------------+-------------+-------------+--------------+----------+----------+----------+-------------+-----------+-------------+-------------+---------------+------------+-------------+--------------+-----------+--------+---------+-----------+-----------+-----------+----------------+-----------+--------
 (0 rows)
 
```

The purpose of step 10 is merely to confirm that the exclusion
constraints dist_exclude_named and local_exclude_named have been
dropped. There’s no need to pull back every column from pg_constraint—we
only care about whether any matching row remains.

- Reduces noise in the output
- Eliminates dependence on the full set of pg_constraint columns (which
can drift across Postgres versions)
- Resolves the pg18 regression diff without altering test expectations

src/test/regress/expected/pg17.out

@@ -1262,15 +1262,17 @@ SET search_path TO pg17;
 ALTER TABLE distributed_partitioned_table DROP CONSTRAINT dist_exclude_named;
 ALTER TABLE local_partitioned_table DROP CONSTRAINT local_exclude_named;
 -- Step 10: Verify the constraints were dropped
-SELECT * FROM pg_constraint WHERE conname = 'dist_exclude_named' AND contype = 'x';
- oid | conname | connamespace | contype | condeferrable | condeferred | convalidated | conrelid | contypid | conindid | conparentid | confrelid | confupdtype | confdeltype | confmatchtype | conislocal | coninhcount | connoinherit | conkey | confkey | conpfeqop | conppeqop | conffeqop | confdelsetcols | conexclop | conbin
+SELECT COUNT(*) FROM pg_constraint WHERE conname = 'dist_exclude_named' AND contype = 'x';
+ count
 ---------------------------------------------------------------------
-(0 rows)
+     0
+(1 row)
 
-SELECT * FROM pg_constraint WHERE conname = 'local_exclude_named' AND contype = 'x';
- oid | conname | connamespace | contype | condeferrable | condeferred | convalidated | conrelid | contypid | conindid | conparentid | confrelid | confupdtype | confdeltype | confmatchtype | conislocal | coninhcount | connoinherit | conkey | confkey | conpfeqop | conppeqop | conffeqop | confdelsetcols | conexclop | conbin
+SELECT COUNT(*) FROM pg_constraint WHERE conname = 'local_exclude_named' AND contype = 'x';
+ count
 ---------------------------------------------------------------------
-(0 rows)
+     0
+(1 row)
 
 -- Step 11: Clean up - Drop the tables
 DROP TABLE distributed_partitioned_table CASCADE;

src/test/regress/sql/pg17.sql

@@ -669,8 +669,8 @@ ALTER TABLE distributed_partitioned_table DROP CONSTRAINT dist_exclude_named;
 ALTER TABLE local_partitioned_table DROP CONSTRAINT local_exclude_named;
 
 -- Step 10: Verify the constraints were dropped
-SELECT * FROM pg_constraint WHERE conname = 'dist_exclude_named' AND contype = 'x';
-SELECT * FROM pg_constraint WHERE conname = 'local_exclude_named' AND contype = 'x';
+SELECT COUNT(*) FROM pg_constraint WHERE conname = 'dist_exclude_named' AND contype = 'x';
+SELECT COUNT(*) FROM pg_constraint WHERE conname = 'local_exclude_named' AND contype = 'x';
 
 -- Step 11: Clean up - Drop the tables
 DROP TABLE distributed_partitioned_table CASCADE;