Bug 27926: (QA follow-up) Switch to using data-order

Bug 27926: (QA follow-up) Switch to using data-order

This patch switches away from using the title attribute for ordering and
instead uses data-order which is supported in modern DataTables.  This
has the effect of allowing our ordering to continue to work but without
adding the unwanted tooltip on hover.

Test plan
1/ Ensure sorting is still working as expected
2/ Hover over any of the date of birth fields and note that you are not
longer faced with a tooltip.
3/ Signoff

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>