Create stable/stein branches for all libraries and client libraries
that do not have them already. The branching point is the most
recent library release.
NB: ironic-lib, kuryr, metalsmith, octavia-lib, python-saharaclient,
python-zunclient and sushy already had stable/stein branches defined.
Change-Id: I2c584e497fb9fc21b3e0f580657b486672608d1e