Disable python-barbicanclient 3.0.0 version

python-barbicanclient 3.0.0 has introduced cliff module, but pins it
to 1.6.1, while global-requirements set it to >=1.7.0, now the whole
OpenStack projects depends on higher version of cliff, but
python-barbicanclient is needed by cinder, then grenade test will
fail because: pkg_resources.DistributionNotFound: cliff==1.6.1

As long as python-barbicanclient maintainers don't provide a patch
for 3.0.0 (which seems not happen FMPOV), we need to disbable this
version.

Change-Id: Idd519fc3aa6e004aa75b56b36ffd125dde20f70e
Related-Bug: #1388414