Bug 33879: Do no longer overwrite interface in check_cookie_auth

Bug 33879: Do no longer overwrite interface in check_cookie_auth

This will only have effect on installations running OPAC and staff
on the same domain name. In that case an OPAC cookie still allows
you to access intranet, and v.v.

Test plan:
Repeat the following steps WITHOUT this patch and WITH it.
Login via OPAC.
Go to staff. Perform an action that logs the interface in e.g. the
statistics table, like a checkout.
Inspect interface in the corresponding table. Observe difference
that this patch makes.

With this patch:
Run t/db_dependent/Auth.t. Should pass again.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Björn Nylén <bjorn.nylen@ub.lu.se>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>