Pin neutron-tempest-plugin for ussuri/victoria jobs

As stable/victoria is in EM phase, and qa team also pinning
tempest 26.1.0 for stable/victoria
- https://review.opendev.org/c/openstack/devstack/+/843295

To have compatible neutron-tempest-plugin version with Tempest
26.1.0, we need to pin neutron-tempest-plugin 1.6.0 version. And
remove the vicrotia job from master gate.

Also same version we need to pin for stable/ussuri also as stable/ussuri
is also pinned with 26.1.0. in the ussuri
- https://review.opendev.org/c/openstack/devstack/+/838051

with 1.8.0, we are facing some incomaptbile code with Tempest 26.1.0
- https://zuul.opendev.org/t/openstack/build/c4d49a80620b44c7ba708e5afebd2b1c

Also, both EM branch facing below error (bug#1948804)
 sudo: guestmount: command not found
and applying the same fix from stable/train
- https://review.opendev.org/c/openstack/neutron-tempest-plugin/+/815518

Depends-On: https://review.opendev.org/c/openstack/devstack/+/838051
Depends-On: https://review.opendev.org/c/openstack/devstack/+/843295

Related-Bug: #1948804

Change-Id: I7d8c1b4cf5c483f1eb4411649c56d6cd8cd3bc66
3 files changed