add non-voting postgresql to tempest and devstack checks

add non-voting postgresql to tempest and devstack checks. Handled
regressions that would have been caught with both of those today, I
think it's time we started getting regular data on these in preparation
for having this be voting gate.

Increase postgresql job to 120 minutes to make it on par with
the normal job we've been running.

Remove explicit DEVSTACK_GATE_CINDER from
gate-tempest-devstack-vm-postgres as this will never be used on existing
stable jobs that need that variable.

Change-Id: Ib538ef60b0b4dada8261792eaa6218a31caa54cc
Reviewed-on: https://review.openstack.org/18850
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: James E. Blair <corvus@inaugust.com>
Approved: James E. Blair <corvus@inaugust.com>
Tested-by: Jenkins