Remove lower-constraints remnants

These were missed in change I3eafc92ba7c7305b1a73d3f96c427ed12c96dbf7.

Change-Id: Idf7148bcf588efbd20352bf2160ecee573156444
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

lower-constraints.txt

@@ -1,9 +0,0 @@
-oslo.config==5.2.0
-oslo.i18n==3.15.3
-enum34==1.0.4
-PrettyTable==0.7.1
-oslotest==3.5.0
-stestr==2.0.0
-oslo.serialization==2.21.1
-oslo.utils==4.5.0
-oslo.policy==2.0.0

tox.ini

@@ -8,7 +8,6 @@ ignore_basepython_conflict = true
 basepython = python3
 usedevelop = True
 setenv =
-   VIRTUAL_ENV={envdir}
   OS_DEBUG=1
   OS_STDOUT_CAPTURE=1
   OS_STDERR_CAPTURE=1
@@ -30,7 +29,7 @@ deps = {[testenv]deps}
 setenv =
   PYTHON=coverage run --source oslo_upgradecheck --parallel-mode
 commands =
-    stestr run '{posargs}'
+  stestr run {posargs}
   coverage combine
   coverage html -d cover
   coverage xml -o cover/coverage.xml
@@ -45,15 +44,6 @@ commands =
   rm -rf doc/build
   sphinx-build -W --keep-going -b html doc/source doc/build/html
 
-[testenv:debug]
-commands = oslo_debug_helper {posargs}
-
-[testenv:lower-constraints]
-deps =
-  -c{toxinidir}/lower-constraints.txt
-  -r{toxinidir}/test-requirements.txt
-  -r{toxinidir}/requirements.txt
-
 [testenv:releasenotes]
 deps = {[testenv:docs]deps}
 whitelist_externals =
@@ -62,9 +52,11 @@ commands =
   rm -rf releasenotes/build
   sphinx-build -a -E -W -d releasenotes/build/doctrees --keep-going -b html releasenotes/source releasenotes/build/html
 
+[testenv:debug]
+commands = oslo_debug_helper {posargs}
+
 [flake8]
 # E123, E125 skipped as they are invalid PEP-8.
-
 show-source = True
 ignore = E123,E125,W504
 builtins = _