Currently functional tests pass in gate just because some calls are
done on real devstack, and passed by chance. We don't need dsvm at all
with pifpaf.
This change fixes this tests and add bindep.txt file for new gate jobs
without dsvm will be setup to ensure this doesn't happen again.
The tox targets pyXX-psql are renamed pyXX-postgresql to match all other jobs names.
Change-Id: I0e6cfb71cc53a47a11a12b5797fe262f9211ce22