This commit adds a test to save the effort of re-setting the tz cookie when it is already set. We also merge the tz cookie script with the one defining session_info. Commit motivated by discussion on PR #55726 closes odoo/odoo#57218 X-original-commit: 0a43d8040f0c5ec8e9728b2e9da8c7d46d7292bb Signed-off-by: Olivier Dony (odo) <odo@openerp.com>