Steps:
- Install Project
- portal view > task

Issue:
- the private task was displayed in the portal view

Cause:
- the domain was not set for the private portal project

Fix:
- displayed task whose project_id is not false
- so private project was not displayed in the portal view

task-3147011

closes odoo/odoo#117617

X-orignal-commit: https://github.com/odoo/odoo/pull/111456/commits/2c00c7d37cf66601e7a25e22d6170973ea78b158


Signed-off-by: Xavier Bol (xbo) <xbo@odoo.com>