Unable to set the default_provider_driver parameter

If you only use the ovn provider with octavia (and set the parameter use_amphora=false) then the default driver still uses amphora instead of ovn.

It is working on the commandline if i specify --provider ovn, but it isn't working from horizon because the default is still amphora.

openstack loadbalancer create --vip-network-id 1073c754-f10f-40dd-8a5f-d5f7fcbc489f --name test
Provider 'amphora' is not enabled

When i set the default_provider_driver = ovn in the api_settings section in octavia.conf, then it is working again.

[api_settings]
{% if options.enable_amphora -%}
enabled_provider_drivers = amphora:The Octavia Amphora driver,ovn:Octavia OVN driver
default_provider_driver = amphora
{% else -%}
enabled_provider_drivers = ovn:Octavia OVN driver
default_provider_driver = ovn
{% endif -%}