YB: workaround to fix 004_pg_dump_parallel.pl test

Test 004_pg_dump_parallel.pl was introduced by commit
2b216da, which states that it teaches
pg_dump to apply load-via-partition-root automatically when detecting
hash-on-enum partitioning.  For some reason, importing commit
96a81c1 causes this detection to stop
working.  This causes the test to fail.

Given YB backup/restore usually uses --include-yb-metadata which causes
enum oids and sort orders to be preserved, YB doesn't really need
load-via-partition-root nor the automatic detection.  Therefore, ignore
the failing auto detection for now and just fix the test by manually
passing --load-via-partition-root to pg_dump.  In the future, this issue
will naturally go away as YB merges to future versions beyond
96a81c1.  At that point, this test
change should be discarded.

Author: jaki

src/bin/pg_dump/t/004_pg_dump_parallel.pl

@@ -49,6 +49,7 @@
 $node->command_ok(
 	[
 		'pg_dump', '-Fd', '--no-sync', '-j2', '-f', "$backupdir/dump1",
+		'--load-via-partition-root',
 		$node->connstr($dbname1)
 	],
 	'parallel dump');
@@ -66,6 +67,7 @@
 		'pg_dump',   '-Fd',
 		'--no-sync', '-j2',
 		'-f',        "$backupdir/dump2",
+		'--load-via-partition-root',
 		'--inserts', $node->connstr($dbname1)
 	],
 	'parallel dump as inserts');