Clean tox.ini
Clean tox.ini

The parameters of the documentation related environments
in tox.ini contain redundant and unnecessary parts.

The doc gate job uses the 'venv', which starts a MongoDB
instance. Nor the doc gate job, neither the others like
packaging, which use this env, need a MongoDB instance.
Therefore the 'deps' and the setup-test-env.sh call were
removed from the 'venv' section.

The 'deps' definition was removed from the 'docs' section
also, as it is unnecessary there.

Change-Id: Icfb3e9f88724553cc52143fd24de25f8bcf243a0

openstack/aodh,froyobin/ceilometer,pkilambi/ceilometer,idegtiarov/ceilometer,r-mibu/ceilometer,pczerkas/aodh,eayunstack/ceilometer,r-mibu/ceilometer,maestro-hybrid-cloud/ceilometer,redhat-openstack/ceilometer,sileht/aodh,Juniper/ceilometer,m1093782566/openstack_org_ceilometer,ityaptin/ceilometer,chungg/aodh,maestro-hybrid-cloud/ceilometer,cernops/ceilometer,luogangyi/Ceilometer-oVirt,openstack/ceilometer,mathslinux/ceilometer,chungg/aodh,openstack/ceilometer,fabian4/ceilometer,eayunstack/ceilometer,idegtiarov/ceilometer,isyippee/ceilometer,luogangyi/Ceilometer-oVirt,pczerkas/aodh,pkilambi/ceilometer,fabian4/ceilometer,isyippee/ceilometer,MisterPup/Ceilometer-Juno-Extension,froyobin/ceilometer,Juniper/ceilometer,mathslinux/ceilometer,redhat-openstack/ceilometer,sileht/aodh,m1093782566/openstack_org_ceilometer,openstack/aodh,ityaptin/ceilometer,MisterPup/Ceilometer-Juno-Extension,cernops/ceilometer