Description of problem:
the amphora instance sending packets over vxlan MTU

Version-Release number of selected component (if applicable):
16.2

How reproducible:
Run a ML2/OVN + VXLAN environment and create loadbalancer 

Steps to Reproduce:
1. deployed overcloud with ML2/OVN + VXLAN


(undercloud) [stack@undercloud ~]$ cat overcloud_deploy.sh 
#!/usr/bin/bash

openstack overcloud deploy --templates \
  -r /home/stack/roles_data.yaml \
  -n /home/stack/network_data.yaml \
  -e /home/stack/templates/scheduler_hints_env.yaml \
  -e /home/stack/templates/node-info.yaml \
  -e /home/stack/containers-prepare-parameter.yaml \
  -e /home/stack/inject-trust-anchor-hiera.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/enable-legacy-telemetry.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/network-isolation.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/network-environment.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/services/octavia.yaml \
  -e /home/stack/templates/custom-network-configuration.yaml \
  -e /home/stack/templates/fencing.yaml \
  -e /usr/share/openstack-tripleo-heat-templates/environments/compute-instanceha.yaml \
  -e /home/stack/templates/post_config.yaml \
  -e /home/stack/templates/neutron-network-type.yaml \
 --ntp-server 192.168.24.254

(undercloud) [stack@undercloud ~]$ cat /home/stack/templates/neutron-network-type.yaml
parameter_defaults:
  NeutronNetworkType: vxlan,vlan

2. (overcloud) [stack@undercloud ~]$ openstack loadbalancer create --name test1 --vip-subnet-id public
(overcloud) [stack@undercloud ~]$ openstack server list --all
+--------------------------------------+----------------------------------------------+--------+--------------------------+----------------------------------------+------------+
| ID                                   | Name                                         | Status | Networks                 | Image                                  | Flavor     |
+--------------------------------------+----------------------------------------------+--------+--------------------------+----------------------------------------+------------+
| c9747646-969d-4fc8-aa53-6dd896b291d2 | amphora-4b79b899-969f-4ba3-a83a-fb8f4569f5a3 | ACTIVE | lb-mgmt-net=172.24.1.243 | octavia-amphora-16.2-20230412.1.x86_64 | octavia_65 |
| 76100584-05ef-4841-b7d1-860f8197910e | amphora-507fd617-8886-4956-9203-8e747e000d93 | ACTIVE | lb-mgmt-net=172.24.2.69  | octavia-amphora-16.2-20230412.1.x86_64 | octavia_65 |
+--------------------------------------+----------------------------------------------+--------+--------------------------+----------------------------------------+------------+
(overcloud) [stack@undercloud ~]$ openstack loadbalancer list 
+--------------------------------------+-------+----------------------------------+-------------+---------------------+----------+
| id                                   | name  | project_id                       | vip_address | provisioning_status | provider |
+--------------------------------------+-------+----------------------------------+-------------+---------------------+----------+
| 5c80f6a8-0e25-4d53-94e9-a204344e5758 | test1 | 3b414446295548ec9726ec79031b064a | 10.1.1.114  | PENDING_CREATE      | amphora  |
+--------------------------------------+-------+----------------------------------+-------------+---------------------+----------+

Actual results:
Counld't create

Expected results:
Create successfully

Additional info: