Fix the barbicanclient installation not from source
- follow the standard installation pattern for barbicanclient:
only clones if it is installed from source. This way it is
possible to install and test barbicanclient from pip
by default, additional jobs can simply add it
- define the repository metadata using the GIT* arrays.
They are also defined by stackrc, but they should be probably
removed from there;
- remove the useless call of configure_barbicanclient (the same
steps are already performed by install_barbicanclient).
Going forward, configure_barbicanclient can be removed
(cherry picked from commit