TrivialFix:In the change[1] os_testr changed under the covers
from using testr to stestr, so that we now get the following
warning:
ostestr.py:120:
UserWarning: No .stestr.conf file found in the CWD.
Please create one to to replace the .testr.conf. You
can find a script to do this in the stestr git repository.
So remove the .testr.conf and add .stestr.conf which was
generated using a utility script as documented here [2].
[1] Id7cb2a39a8308f1413608dcf19273a1d7f33592e
[2] https://media.readthedocs.org/pdf/stestr/stable/stestr.pdf
Change-Id: I084215311928c0e66d45977748e5a2263bbc1444