[FIX] project: fix portal task groupby

In the portal view of tasks, we set a default groupby in _prepare_task_values to project.
However, since this method is called every time we change the groupby, it is effectively
impossible to group by anything other than project.

This commit fixes this so that it is possible to select other groupbys.

Task-3438490

closes odoo/odoo#134378

X-original-commit: 02629788f24efb4646703cf94f1a8c603179e185
Related: odoo/enterprise#46945
Signed-off-by: Xavier Bol (xbo) <xbo@odoo.com>

addons/project/controllers/portal.py

@@ -47,9 +47,9 @@ class ProjectCustomerPortal(CustomerPortal):
             project=project,
             task_url=f'projects/{project.id}/task',
         )
-        # default value is set to 'project' in _prepare_tasks_values, so we have to set it to 'none' here.
+
         if not groupby:
-            values['groupby'] = 'none'
+            values['groupby'] = 'project' if self._display_project_groupby(project) else 'none'
 
         return self._get_page_view_values(project, access_token, values, 'my_projects_history', False, **kwargs)
 
@@ -291,7 +291,7 @@ class ProjectCustomerPortal(CustomerPortal):
             values['milestone'] = {'label': _('Milestone'), 'order': 'milestone_id', 'sequence': 7}
         return values
 
-    # Meant to be overriden in documents_project
+    # Meant to be overridden in documents_project
     def _display_project_groupby(self, project):
         return not project