Remove unused jenkins arguments from tox.ini

These do not match the established testing patterns for OpenStack and
seem to be quite redundant. They also mention nosetests which is no
longer used.

Change-Id: I874a226b515f1a8ad24136eba81a40fc170435b9
Refactor instance tests to share common code

Change-Id: I565f6aee43d07f3fc451538ca02f9398eedebaf3
Merge "Refactor instance tests to share common code"
Merge "Remove unused jenkins arguments from tox.ini"