added check in ndb tests that require "default" cluster running

i.e. ndb_restore

mysql-test/include/ndb_default_cluster.inc

+-- require r/ndb_default_cluster.require
+disable_query_log;
+show status like "Ndb_connected_host";
+enable_query_log;

mysql-test/r/ndb_default_cluster.require

+Variable_name	Value
+Ndb_connected_host	localhost

mysql-test/t/ndb_restore.test

 -- source include/have_ndb.inc
+-- source include/ndb_default_cluster.inc
 
 --disable_warnings
 use test;