Remove lower-constraints remnants

These were missed in change: I62d911111b54976a9df726c48f593a52e275fe6c

Change-Id: I4f07ec3617d5e73abbabd45234fe4e67ec395fdb

lower-constraints.txt

@@ -1,29 +0,0 @@
-alabaster==0.7.10
-Babel==2.3.4
-bandit==1.4.0
-coverage==4.0
-docutils==0.11
-extras==1.0.0
-fixtures==3.0.0
-gitdb==0.6.4
-GitPython==1.0.1
-imagesize==0.7.1
-importlib_metadata==1.7.0
-Jinja2==2.10
-linecache2==1.0.0
-MarkupSafe==1.0
-pbr==2.0.0
-Pygments==2.2.0
-python-mimeparse==1.6.0
-python-subunit==1.0.0
-pytz==2013.6
-PyYAML==3.12
-requests==2.14.2
-smmap==0.9.0
-snowballstemmer==1.2.1
-Sphinx==2.0.0
-sphinxcontrib-websupport==1.0.1
-stestr==2.0.0
-testtools==2.2.0
-traceback2==1.4.0
-unittest2==1.1.0

tox.ini

@@ -52,8 +52,3 @@ deps = bindep
 commands = bindep test
 usedevelop = False
 
-[testenv:lower-constraints]
-deps =
-  -c{toxinidir}/lower-constraints.txt
-  -r{toxinidir}/test-requirements.txt
-  -r{toxinidir}/requirements.txt