MB-10721 session cookie should not expire in browser

.. since it already set to expire on server

Change-Id: I3fb7491bf92da55629dfd867cf9da2d903fcb94b
Reviewed-on: http://review.couchbase.org/35920
Tested-by: Artem Stemkovski <artem@couchbase.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>