HPCC-8927 Lazy open should default to smart mode

Especially now that the lazy opening of indexes takes account of the lazyOpen
flag, it seems more sensible to default to 'smart' behaviour rather than off.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>
Merge pull request #4070 from richardkchapman/roxie-lazy-smart

HPCC-8927 Lazy open should default to smart mode

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>