chore: remove unused variables (#9742)

Author: jennifer-richards

ietf/meeting/models.py

@@ -956,8 +956,6 @@ class Meta:
     def __str__(self):
         return u"%s -> %s-%s" % (self.session, self.document.name, self.rev)
 
-constraint_cache_uses = 0
-constraint_cache_initials = 0
 
 class SessionQuerySet(models.QuerySet):
     def with_current_status(self):