Remove redundant result assignment in 004_sync.pl.

Author: Peter Smith
Discussion: http://postgr.es/m/CAHut+PuTNdxnpn24s6jfPDe+fKJoe3M-CoNv-DFsZmJN-ed0Xw@mail.gmail.com

Author: Amit Kapila

src/test/subscription/t/004_sync.pl

@@ -156,7 +156,7 @@
 	"CREATE SUBSCRIPTION tap_sub CONNECTION '$publisher_connstr' PUBLICATION tap_pub"
 );
 
-$result = $node_subscriber->poll_query_until('postgres', $started_query)
+$node_subscriber->poll_query_until('postgres', $started_query)
   or die "Timed out while waiting for subscriber to start sync";
 
 # DROP SUBSCRIPTION must clean up slots on the publisher side when the