Currently, the value stored in the services_region cookie is ignored
when logging into horizon. This causes confusion for users that have
previously selected one region, to find themselves in a different
region after their token expires and are forced to log in again.
This change sets the services_region session value to the value present
in the cookie, with a fallback to the login region.
Closes-bug: #2040455
Change-Id: I051648844bf8dffce792ff553e9949285b1be6d4
Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>