[FIX] project : apply project notification preferences to task

Steps :
Go to a Project's settings.
In your 'Following' preferences, uncheck 'Task Rating'.
Create a new Task in this Project and see your preferences.

Issue :
Task Rating is checked.

Cause :
The default value of project's task rating notification is True.
The value of its task's is supposed to be inheritted from there.
Yet, this inherittance only happen when default is False.

Fix :
Set default to False.

opw-282497

closes odoo/odoo#89929

Signed-off-by: Laurent Stukkens (ltu) <ltu@odoo.com>