Remove unused refresh_security_group_members() call

This call was replaced with refresh_instance_security_groups() in
compute rpc version 1.41(!) Since we just reached version 4.0 it
should be fairly safe to just remove all traces of this without
backwards compatibility being an issue.

The original change that replaced and made this call no longer being
used was commit 2afbbab23a.

Change-Id: I60d314f68a984fa8e6d36f46b5ae595f0afabe73

nova/virt/firewall.py

@@ -94,14 +94,6 @@ class FirewallDriver(object):
         """
         raise NotImplementedError()
 
-    def refresh_security_group_members(self, security_group_id):
-        """Refresh security group members from data store
-
-        Gets called when an instance gets added to or removed from
-        the security group.
-        """
-        raise NotImplementedError()
-
     def refresh_instance_security_rules(self, instance):
         """Refresh security group rules from data store
 
@@ -422,10 +414,6 @@ class IptablesFirewallDriver(FirewallDriver):
     def instance_filter_exists(self, instance, network_info):
         pass
 
-    def refresh_security_group_members(self, security_group):
-        self.do_refresh_security_group_rules(security_group)
-        self.iptables.apply()
-
     def refresh_security_group_rules(self, security_group):
         self.do_refresh_security_group_rules(security_group)
         self.iptables.apply()