At the moment quite vital arguments, such as region_name and
valid_interfaces, are ignored by the plugin, which results in
inconsistent behaviour with Octavia when trying to interact with
Neutron.
For instance, while Octavia connects to Neutron through the internal
endpoint, the plugin still tries to reach it through the public one,
ignoring options defined in [service_auth] and [neutron] sections.
This patch is basically a copy-paste from Octavia [1].
[1] https://review.opendev.org/c/openstack/octavia/+/905794
Closes-Bug: #2110488
Related-Bug: #2049551
Change-Id: I3a98825e40143dfa9017ca512a27197c48c31ee9
7a17cd1ae3