TT#30500 subscriberregitrations: increase flush timeout

* flush timeout is increased from 5 to 30 seconds

cherry-picked to mr5.5 (see TT#38607)

Change-Id: Ife10172bc8f169822247a1bd8ba48b30c2095f9c
(cherry picked from commit bead4cb85e)

lib/NGCP/Panel/Role/API/SubscriberRegistrations.pm

@@ -198,7 +198,7 @@ sub fetch_item {
     return unless $sub;
 
     my $item;
-    my $flush_timeout = 5;
+    my $flush_timeout = 30;
 
     while ($flush_timeout) {
         $item = $self->_item_by_aor($c, $sub, $form->values->{contact});