[IMP] calendar: set record name as default when scheduling a meeting-based activity

Purpose of this commit to improve scheduling of meetings with activities.
If summary is empty use record's name as name of meeting to speedup the
flow.

This commit is related to task ID 1838315

addons/calendar/models/mail_activity.py

@@ -23,7 +23,7 @@ class MailActivity(models.Model):
             'default_activity_type_id': self.activity_type_id.id,
             'default_res_id': self.env.context.get('default_res_id'),
             'default_res_model': self.env.context.get('default_res_model'),
-            'default_name': self.summary,
+            'default_name': self.summary or self.res_name,
             'default_description': self.note and tools.html2plaintext(self.note) or '',
             'default_activity_ids': [(6, 0, self.ids)],
         }