[FIX] calendar: fix traceback for calendar private event

Currently when other users view the private event of
another user it display the name of the private event as
'false' instead of 'busy' and onclick of event it generates
traceback.

so to fix it added display_name in condition of read because
the event name displayed in calendar view(previously name) is
replace by display_name in commit 369c20a99b

Task-2144553

Closes: #41157
X-original-commit: 1ec853751bd995449619585db8e17f582ba5e5bc

addons/calendar/models/calendar.py

@@ -1696,7 +1696,7 @@ class Meeting(models.Model):
                             r[f] = []
                         else:
                             r[f] = False
-                    if f == 'name':
+                    if f in ['name', 'display_name']:
                         r[f] = _('Busy')
 
         for r in result: