Drop lower-constraints.txt and its testing

As discussed in TC PTG[1] and TC resolution[2], we are
dropping the lower-constraints.txt file and its testing.
We will keep lower bounds in the requirements.txt file but
with a note that these are not tested lower bounds and we
try our best to keep them updated.

[1] https://etherpad.opendev.org/p/tc-zed-ptg#L326
[2] https://governance.openstack.org/tc/resolutions/20220414-drop-lower-constraints.html#proposal

Change-Id: I2eea42d3909896ea8606dc9cde681b2cc1cfb62f

lower-constraints.txt

@@ -1,72 +0,0 @@
-appdirs==1.3.0
-asn1crypto==0.23.0
-bandit==1.1.0
-cffi==1.14.0
-cliff==2.8.0
-cmd2==0.8.0
-coverage==4.0
-cryptography==2.1
-debtcollector==1.2.0
-extras==1.0.0
-fasteners==0.7.0
-fixtures==3.0.0
-flake8-docstrings==0.2.1.post1
-future==0.16.0
-gitdb==0.6.4
-GitPython==1.0.1
-idna==2.6
-importlib_metadata==1.7.0
-iso8601==0.1.11
-jsonschema==2.6.0
-keyring==5.5.1
-keystoneauth1==3.4.0
-linecache2==1.0.0
-lxml==4.5.0
-mccabe==0.2.1
-mock==2.0.0
-monotonic==0.6
-mox3==0.20.0
-msgpack-python==0.4.0
-netaddr==0.7.18
-netifaces==0.10.4
-oauthlib==0.6.2
-os-client-config==1.28.0
-oslo.concurrency==3.25.0
-oslo.config==5.2.0
-oslo.context==2.19.2
-oslo.i18n==3.15.3
-oslo.log==3.36.0
-oslo.serialization==2.18.0
-oslo.utils==3.33.0
-oslotest==3.2.0
-packaging==20.4
-paramiko==2.0.0
-pbr==2.0.0
-pep257==0.7.0
-prettytable==0.7.2
-pyasn1==0.1.8
-pycparser==2.18
-pyinotify==0.9.6
-pyparsing==2.1.0
-pyperclip==1.5.27
-python-dateutil==2.5.3
-python-mimeparse==1.6.0
-python-subunit==1.0.0
-pytz==2013.6
-PyYAML==3.13
-requests-mock==1.2.0
-requests==2.14.2
-requestsexceptions==1.2.0
-rfc3986==0.3.1
-six==1.10.0
-smmap==0.9.0
-stevedore==1.20.0
-tempest==17.1.0
-stestr==2.0.0
-testresources==2.0.0
-testscenarios==0.4
-testtools==2.2.0
-traceback2==1.4.0
-unittest2==1.1.0
-urllib3==1.21.1
-wrapt==1.7.0

requirements.txt

@@ -1,3 +1,7 @@
+# Requirements lower bounds listed here are our best effort to keep them up to
+# date but we do not test them so no guarantee of having them all correct. If
+# you find any incorrect lower bounds, let us know or propose a fix.
+
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.

tox.ini

@@ -92,8 +92,3 @@ import_exceptions =
 deps = bindep
 commands = bindep test
 
-[testenv:lower-constraints]
-deps =
-  -c{toxinidir}/lower-constraints.txt
-  -r{toxinidir}/test-requirements.txt
-  -r{toxinidir}/requirements.txt