Description of problem:
Allow creation of volume-based amphora. Many deploy production uses volume-based instances because of more flexibility. Octavia will create volume and attach this to the amphora.

Version-Release number of selected component (if applicable):
Red Hat OpenStack Platform - 16.1.z

Expected results:
Able to use volume-based amphora

Additional info:
As per link: https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/16.1/html/networking_guide/sec-octavia#octavia-feature-support-matrix
Volume-Based Amphora has no support.

The feature is implemented upstream as per below links:
https://docs.openstack.org/releasenotes/octavia/train.html#relnotes-5-0-0-stable-train
https://review.opendev.org/q/topic:%22volume-based%22