Remove testrepository and .testr.conf

This commit is a follow-up of "switch to using stestr"
which was merged already [1].
After switch to using stestr, testrepository and .testr.conf
are unnecessary and should be removed.

[1] https://review.openstack.org/576862

Change-Id: I9f35e4f1341848a62a143b7f7150f2b845575861

.gitignore

@@ -1,6 +1,5 @@
 *.egg*
 *.pyc
 .tox
-.testrepository
 simulator
 .stestr

.testr.conf

@@ -1,7 +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:-600} \
-             ${PYTHON:-python} -m subunit.run discover ${OS_TEST_PATH:-./ceilosca/ceilometer/tests} -t . $LISTOPT $IDOPTION
-test_id_option=--load-list $IDFILE
-test_list_option=--list

test-requirements.txt

@@ -1,6 +1,5 @@
 git+https://github.com/openstack/ceilometer.git@master#egg=ceilometer
 mock>=1.2
-testrepository>=0.0.18
 testscenarios>=0.4
 testtools>=1.4.0
 oslotest>=2.15.0 # Apache-2.0