Stable jobs: run the tests on victoria, remove stein
Stable jobs: run the tests on victoria, remove stein

Update the list of tested stable branches (excluding stein which is EM).
The nodesets for the stable branches are now pinned because
their testing environment are well defined and won't change.

Also, remove the -py3 suffix: those jobs are all -py3 based
(the suffix was mostly requires in the transitional time
between py2 and py3).

Change-Id: I48f8574960df51fc47f80fa17091fd13ec71aa99

openstack/devstack-plugin-ceph