Bug 30911: Datatables error on course-details.pl after adding a bib-level course...

Bug 30911: Datatables error on course-details.pl after adding a bib-level course reserve

This patch removes the colspan from biblio-level course reserves rows in
favor of adding a style to the message's container allowing it to
overflow across table cells.

To test, apply the patch and go to course reserves.

1. If necessary, add a new course.
2. View the details of the course and add a reserve using the
   biblionumber option to add the reserve at the bibliographic level.
3. Add a notes if you want, then click "Save."
4. Return to the course detail view.
5. In the table of reserves your biblio-level reserve should have a
   message starting in the "Barcode" column and overflowing across other
   item information columns, "Item information is not available for
   record-level course reserve."
6. Try adding multiple item-level and biblio-level reserves to the same
   course to confirm that the information displays well in those cases.

Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>