[devtools] make test db name for postgresql process-specific In case we run two tests concurrently on the same cluster, better not use the same db name for both.

usr/bin/cubicweb-ctl usr/bin/
usr/lib/PY_VERSION/*-packages/cubicweb/cwctl.py
../cubicweb-ctl.bash_completion etc/bash_completion.d/cubicweb-ctl