[FIX] calendar: group_by with calendar

Delete the code introduced by 656f8241d5
Group by didn't work in calendar tree view, group of records showed (0)
as number of related records for each group.

closes #7602
opw:644735

addons/calendar/calendar.py

@@ -1662,12 +1662,6 @@ class calendar_event(osv.Model):
         virtual_id = context.get('virtual_id', True)
         context.update({'virtual_id': False})
         res = super(calendar_event, self).read_group(cr, uid, domain, fields, groupby, offset=offset, limit=limit, context=context, orderby=orderby, lazy=lazy)
-        for result in res:
-            #remove the count, since the value is not consistent with the result of the search when expand the group
-            for groupname in groupby:
-                if result.get(groupname + "_count"):
-                    del result[groupname + "_count"]
-            result.get('__context', {}).update({'virtual_id': virtual_id})
         return res
 
     def read(self, cr, uid, ids, fields=None, context=None, load='_classic_read'):