[occm] Add `amphorav2` support in loadbalancer provider array

[manuelchichi]

/kind feature

What happened:
When attempting to specify amphorav2 as the load balancer provider using the annotation service.beta.kubernetes.io/openstack-load-balancer-provider or modifying the ccm cloud config with [LoadBalancer] lb-provider=amphorav2, the controller fails to recognize it as a valid provider. The current supportedLBProvider array only includes "amphora", "octavia", "ovn", and "f5" as here

What you expected to happen:
The controller should accept amphorav2 as a valid load balancer provider, as it is a commonly used and supported option in OpenStack Octavia.

How to reproduce it:
Set in ingress annotations:

service.beta.kubernetes.io/openstack-load-balancer-provider: amphorav2

Or in ccm cloud config:

[LoadBalancer]
lb-provider=amphorav2

Anything else we need to know?:
I have tested this locally and confirmed that adding amphorav2 to the array resolves the issue and allows proper provisioning.

Environment:

• openstack-cloud-controller-manager (or other related binary) version: 1.33.1
• OpenStack version: all