Reenable diskless for faster mysql-test-run

  if [ -z "$USE_RUNNING_NDBCLUSTER" ]

  then

    echo "Starting ndbcluster"

    ./ndb/ndbcluster --port-base=$NDBCLUSTER_PORT --small --initial --data-dir=$MYSQL_TEST_DIR/var || exit 1

    ./ndb/ndbcluster --port-base=$NDBCLUSTER_PORT --small --diskless --initial --data-dir=$MYSQL_TEST_DIR/var || exit 1

    NDB_CONNECTSTRING="host=localhost:$NDBCLUSTER_PORT"

    export NDB_CONNECTSTRING

  else