[IMP] mail_activity_team: filter fix, follow-up comments

Taken from the 16.0 branch after the merge of OCA#1280
which was picked for the migration of this module for 17.0 in an earlier stage.

mail_activity_team/models/mail_activity.py

@@ -26,7 +26,9 @@ def _get_default_team_id(self, user_id=None):
     )
 
     team_id = fields.Many2one(
-        comodel_name="mail.activity.team", default=lambda s: s._get_default_team_id()
+        comodel_name="mail.activity.team",
+        default=lambda s: s._get_default_team_id(),
+        index=True,
     )
 
     @api.onchange("user_id")

mail_activity_team/models/mail_activity_mixin.py

@@ -94,7 +94,7 @@ def _compute_my_activity_date_deadline(self):
                     activity.date_deadline
                     for activity in record.activity_ids
                     if activity.user_id.id == record.env.uid
-                    or activity.team_id.id in record.env.user.activity_team_ids.ids
+                    or activity.team_id in record.env.user.activity_team_ids
                 ),
                 False,
             )

mail_activity_team/tests/test_mail_activity_team.py

@@ -322,6 +322,9 @@ def test_schedule_activity_from_server_action(self):
         self.assertEqual(partner.activity_ids[-1].team_id, self.team2)
 
     def test_my_activity_date_deadline(self):
+        """This test case checks
+        - if the team activities are properly filtered
+        """
         today = date.today()
         self.act2.write(
             {