Remove expensive test of postgres_fdw batch inserts

The test inserted 70k rows into a foreign table, in order to verify
correct behavior with more than 65535 parameters, and was added in
response to a bug report.

However, this is rather expensive, especially when running the tests
under valgrind, CLOBBER_CACHE_ALWAYS etc. It doesn't seem worth it to
keep running the test, so remove it from all branches (14+).

Backpatch-through: 14
Discussion: https://postgr.es/m/2131017.1623451468@sss.pgh.pa.us

Author: tvondra

contrib/postgres_fdw/expected/postgres_fdw.out

@@ -10346,17 +10346,6 @@ SELECT COUNT(*) FROM ftable;
     34
 (1 row)
 
-TRUNCATE batch_table;
-DROP FOREIGN TABLE ftable;
--- try if large batches exceed max number of bind parameters
-CREATE FOREIGN TABLE ftable ( x int ) SERVER loopback OPTIONS ( table_name 'batch_table', batch_size '100000' );
-INSERT INTO ftable SELECT * FROM generate_series(1, 70000) i;
-SELECT COUNT(*) FROM ftable;
- count 
--------
- 70000
-(1 row)
-
 TRUNCATE batch_table;
 DROP FOREIGN TABLE ftable;
 -- Disable batch insert

contrib/postgres_fdw/sql/postgres_fdw.sql

@@ -3341,13 +3341,6 @@ SELECT COUNT(*) FROM ftable;
 TRUNCATE batch_table;
 DROP FOREIGN TABLE ftable;
 
--- try if large batches exceed max number of bind parameters
-CREATE FOREIGN TABLE ftable ( x int ) SERVER loopback OPTIONS ( table_name 'batch_table', batch_size '100000' );
-INSERT INTO ftable SELECT * FROM generate_series(1, 70000) i;
-SELECT COUNT(*) FROM ftable;
-TRUNCATE batch_table;
-DROP FOREIGN TABLE ftable;
-
 -- Disable batch insert
 CREATE FOREIGN TABLE ftable ( x int ) SERVER loopback OPTIONS ( table_name 'batch_table', batch_size '1' );
 EXPLAIN (VERBOSE, COSTS OFF) INSERT INTO ftable VALUES (1), (2);