Right now, if someone changes the `crm.pls_start_date` system parameter
to something that is not valid, opening a settings gives you traceback.
This commit improves the behavior by making sure that the compute field on
settings page `predictive_lead_scoring_start_date` always contains a valid
date. For doing so, if the system parameter is not a valid date(or not set
or deleted), we set the above field to the date 8 days prior to current
date, and thus, when saving the settings, the system parameter is again
set with a valid date.
closesodoo/odoo#66988
Taskid: 2448248
X-original-commit: 19577c40f8f2878286ef63da5d30b341d7ab5cbf
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>