Remove lower-constraints remnants

These were missed in change: If2a9cf05f382ae28846b95e5bb29669ee57f9bcd

Change-Id: I364eea549d42e75471288c597bd9dd8094d87c64
(cherry picked from commit a24a5a0676)

lower-constraints.txt

@@ -1,30 +0,0 @@
-appdirs==1.3.0
-Babel==2.3.4
-bandit==1.4.0
-coverage==4.0
-debtcollector==1.2.0
-extras==1.0.0
-fixtures==3.0.0
-gitdb==0.6.4
-GitPython==1.0.1
-iso8601==0.1.11
-keystoneauth1==3.4.0
-linecache2==1.0.0
-mox3==0.20.0
-os-client-config==1.28.0
-oslotest==3.2.0
-pbr==2.0.0
-python-mimeparse==1.6.0
-python-subunit==1.0.0
-pytz==2013.6
-PyYAML==3.12
-requests==2.14.2
-requestsexceptions==1.2.0
-six==1.10.0
-smmap==0.9.0
-stestr==2.0.0
-stevedore==1.20.0
-testtools==2.2.0
-traceback2==1.4.0
-unittest2==1.1.0
-wrapt==1.7.0

tox.ini

@@ -54,8 +54,3 @@ commands =
   rm -rf releasenotes/build
   sphinx-build -a -E -W -d releasenotes/build/doctrees --keep-going -b html releasenotes/source releasenotes/build/html
 
-[testenv:lower-constraints]
-deps =
-  -c{toxinidir}/lower-constraints.txt
-  -r{toxinidir}/test-requirements.txt
-  -r{toxinidir}/requirements.txt