Use TOX_CONSTRAINTS_FILE
Use TOX_CONSTRAINTS_FILE

UPPER_CONSTRAINTS_FILE is old name and deprecated.
This allows to use upper-constraints file as more
readable way instead of UPPER_CONSTRAINTS_FILE=<lower-constraints file>.
For more info. please refer [1].

[1] https://zuul-ci.org/docs/zuul-jobs/python-roles.html#rolevar-tox.tox_constraints_file

Change-Id: I956f55f4c95c7ec892430a7fd0bfda4a6819aba9

openstack/senlin-dashboard,stackforge/senlin-dashboard,stackforge/senlin-dashboard,openstack/senlin-dashboard,openstack/senlin-dashboard,openstack/senlin-dashboard,stackforge/senlin-dashboard