Prettify tox output for functional tests
Prettify tox output for functional tests

Change I6a079ad introduced some magic to enable showing test output
as the test run. Do the same for *-functional tests too, by reusing
the default testenv

Change-Id: I6d1ede1c66e7b62c68449224f274417a5d66c12f

moshele/old-networking-mlnx