Ignore admin user in external LDAP

as it's already excluded in Zimbra

zmldapsync/zmldapsync.pl

@@ -314,6 +314,11 @@ DOMAIN: foreach my $domain ( keys $conf->{domains} ) {
   # or which exist in both but need to be updated
   foreach my $user ( keys $ext_users ) {
     my $attrs = '';
+    # Ignore admin
+    if ( $user eq 'admin' ) {
+      log_verbose( "Skiping admin user");
+      next;
+    }
     if ( defined $zim_users->{$user} ) {
 
       # User exists in Zimbra, lets check its attribute are up to date