switch documentation job to new PTI
switch documentation job to new PTI

This is a mechanically generated patch to switch the documentation
jobs to use the new PTI versions of the jobs as part of the
python3-first goal.

See the python3-first goal document for details:
https://governance.openstack.org/tc/goals/stein/python3-first.html

Change-Id: Id9fe2f43e7202014420a758da009497a5684ad5b
Story: #2002586
Task: #24319

openstack/openstack-ansible-memcached_server,openstack/openstack-ansible-memcached_server