Bug 29949: Remove use of title-numeric sorting routine from OPAC datatables JS

Bug 29949: Remove use of title-numeric sorting routine from OPAC datatables JS

This patch removes the use of a specific "title-numeric" sorting routine
from the DataTables configuration of the "Most popular" table. We can
use a "data-order" attribute instead.

The patch also removes the now unused code from our custom DataTables JS
file in both the OPAC and the staff interface (where it was unused).

To test, apply the patch and make sure the OpacTopissue system
preference is enabled.

- In the OPAC, view the "Most popular" page.
- Change the filter settings, if necessary, to get multiple results.
- In the results table, confirm that sorting by number of checkouts
  still works correctly.

A search of the code for instances of "title-numeric" should return only
one in a comment in the official DataTables library.

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>