Drop EOL branches from job definitions

Stein, Train and Ussuri branches are all completely EOL not and should
be dropped.

Depends-On: https://review.opendev.org/c/openstack/devstack-plugin-nfs/+/910217
Change-Id: If1bcde49c9aabd380e4f3709b0db38a9f57ec2d7
2 files changed