Revert test added by commit d2070380.

This test was trying to test the mechanism to release kernel FDs as needed
to get us under the max_safe_fds limit in case of spill files.  To do that,
it needs to set max_files_per_process to a very low value which doesn't
even permit starting of the server in the case when there are a few already
opened files.  This test also won't work on platforms where we use one FD
per semaphore.

Backpatch-through: 10, till where this test was added
Discussion:
https://postgr.es/m/CAA4eK1LHhERi06Q+MmP9qBXBBboi+7WV3910J0aUgz71LcnKAw@mail.gmail.com
https://postgr.es/m/6485.1578583522@sss.pgh.pa.us

src/test/recovery/t/006_logical_decoding.pl

@@ -7,7 +7,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 11;
+use Test::More tests => 10;
 use Config;
 
 # Initialize master node
@@ -135,43 +135,5 @@ is($node_master->psql('postgres', 'DROP DATABASE otherdb'),
 is($node_master->slot('otherdb_slot')->{'slot_name'},
 	undef, 'logical slot was actually dropped with DB');
 
-# Test to ensure that we don't run out of file descriptors even if there
-# are more spill files than maxAllocatedDescs.
-
-# Set max_files_per_process to a small value to make it more likely to run out
-# of max open file descriptors.
-$node_master->safe_psql('postgres',
-	'ALTER SYSTEM SET max_files_per_process = 26;');
-$node_master->restart;
-
-$node_master->safe_psql(
-	'postgres', q{
-do $$
-BEGIN
-    FOR i IN 1..10 LOOP
-        BEGIN
-            INSERT INTO decoding_test(x) SELECT generate_series(1,5000);
-        EXCEPTION
-            when division_by_zero then perform 'dummy';
-        END;
-    END LOOP;
-END $$;
-});
-
-$result = $node_master->safe_psql('postgres',
-	qq[
-set logical_decoding_work_mem to 64; -- generate plenty of .spill files
-SELECT data from pg_logical_slot_get_changes('test_slot', NULL, NULL)
-    WHERE data LIKE '%INSERT%' ORDER BY lsn LIMIT 1;
-]);
-
-$expected = q{table public.decoding_test: INSERT: x[integer]:1 y[text]:null};
-is($result, $expected, 'got expected output from spilling subxacts session');
-
-# Reset back max_files_per_process
-$node_master->safe_psql('postgres',
-	'ALTER SYSTEM SET max_files_per_process = DEFAULT;');
-$node_master->restart;
-
 # done with the node
 $node_master->stop;