tests: replace .testr.conf with .stestr.conf

In this 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

TrivialFix

Change-Id: I6bb369624c4a790242022e203e771a77ffe06cf5

.gitignore

@@ -7,6 +7,7 @@
 *.swp
 .manila-venv
 .coverage
+.stestr/*
 .testrepository
 .tox
 .venv

.stestr.conf

@@ -0,0 +1,3 @@
+[DEFAULT]
+test_path=./manila/tests
+top_dir=./

.testr.conf

@@ -1,8 +0,0 @@
-[DEFAULT]
-test_command=OS_STDOUT_CAPTURE=${OS_STDOUT_CAPTURE:-1} \
-             OS_STDERR_CAPTURE=${OS_STDERR_CAPTURE:-1} \
-             OS_TEST_TIMEOUT=${OS_TEST_TIMEOUT:-60} \
-             OS_LOG_CAPTURE=${OS_LOG_CAPTURE:-1} \
-             ${PYTHON:-python} -m subunit.run discover -t ./ ./manila/tests $LISTOPT $IDOPTION
-test_id_option=--load-list $IDFILE
-test_list_option=--list