[FIX] project: fix groupby by none issue in project sharing

Steps:
- Go to portal and select tasks and search anything in search bar.
- Showing  no tasks available
- choose group by none and search anything it will show table labels.

Fix:
shows warning when there is no record when groupby by none.

task-3183771

closes odoo/odoo#128181

X-original-commit: cf1c7c7b
Signed-off-by: Xavier Bol (xbo) <xbo@odoo.com>