Description of problem:
When we switch back and forth between stateful to stateless security group, the ACL rules in OVN are not updated.

The new ACL rules are created according to the SG mode though.

Version-Release number of selected component (if applicable):

openstack-neutron-common-15.3.5-2.20210608154815.el8ost.4.noarch
openstack-neutron-15.3.5-2.20210608154815.el8ost.4.noarch
python3-neutron-15.3.5-2.20210608154815.el8ost.4.noarch
openstack-neutron-ml2-15.3.5-2.20210608154815.el8ost.4.noarch

How reproducible:
Always

Steps to Reproduce:
1. The pre created SG is stateful
$  openstack security group show default -c stateful -f value
True

In a controller, we can list the ACLs as "allow-related"
[heat-admin@overcloud-controller-0 ~]$ sudo podman exec -ti ovn_controller ovn-nbctl list ACL

_uuid               : e31f56a6-a373-4f0f-b690-dafd7b964d99
action              : allow-related
direction           : to-lport
external_ids        : {"neutron:security_group_rule_id"="459deec0-a4b2-4c5a-af5d-fe6c66346fef"}
log                 : false
match               : "outport == @pg_26f1270b_efaa_4948_826d_c227e7808ca5 && ip4 && ip4.src == 0.0.0.0/0 && udp"
meter               : []
name                : []
priority            : 1002
severity            : []



2. Switch to stateless SG:
$ openstack security group set --stateless default

Yet, the "list ACL" command shows that the rule still uses conntrack (allow-related).

3. We create a new rule:
openstack security group rule create default --protocol tcp --dst-port 22:22 --remote-ip 0.0.0.0/0


Actual results:

The rules are a mix of allow-related and allow-stateless:

[heat-admin@overcloud-controller-0 ~]$ sudo podman exec -ti ovn_controller ovn-nbctl list ACL


_uuid               : fb970be6-493c-424a-b133-66dcbe3aedee
action              : allow-stateless
direction           : to-lport
external_ids        : {"neutron:security_group_rule_id"="4ef8bc9c-7450-43c5-9878-c01037b72240"}
log                 : false
match               : "outport == @pg_26f1270b_efaa_4948_826d_c227e7808ca5 && ip4 && ip4.src == 0.0.0.0/0 && tcp && tcp.dst == 22"
meter               : []
name                : []
priority            : 1002
severity            : []

_uuid               : 18cc8207-6489-49d9-bb57-31ed04b04726
action              : allow-related
direction           : to-lport
external_ids        : {"neutron:security_group_rule_id"="2698c7f8-176e-4bfb-b6c6-7314272e6dd8"}
log                 : false
match               : "outport == @pg_26f1270b_efaa_4948_826d_c227e7808ca5 && ip4 && ip4.src == 0.0.0.0/0 && tcp"
meter               : []
name                : []
priority            : 1002
severity            : []



Expected results:
All rules should be "allow-stateless" or "allow-related" when we update the security group to stateless or stateful.