Add missing env vars from unit test job

This commit fixes an oversight in the tox job definitions for unit
tests. Because for better or worse we still use oslotest as the base
test class for tempest's unit tests the stdout, stderr, and logging
capture fixtures are only enabled by an env var. We were never setting
that, so these things weren't captured. This commit fixes the oversight
to enable the capture of these once again.

Change-Id: I81e4077dfda9e9a8a8001f52955ab0164f39d31d
1 file changed