Bug 30449: Add missing FK constraint on borrower_attribute_types

Bug 30449: Add missing FK constraint on borrower_attribute_types

Old Koha databases probably have it, newer ones might not.
See also BZ description.

Test plan:
[1} Check SHOW CREATE TABLE borrower_attribute_types to see if you
    have any index and FK constraint on category_code.
[2] Run updatedatabase.
[3] If you had category_code_fk, it should be replaced.
[4] Remove index and constraint again using things like:
    alter table borrower_attribute_types drop constraint `borrower_attribute_types_ibfk_1`;
    alter table borrower_attribute_types drop index category_code;
[5] Run updatedatabase.
[6] You should have KEY category_code and FK borrower_attribute_types_ibfk_1.
[7] Run updatedatabase. Idempotent, no changes.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>