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: Ieba7daf39fa3323e8c9a7396747449f24189fcd5

.zuul.yaml

@@ -9,7 +9,6 @@
       - check-requirements
       - integrated-gate-placement
       - openstack-cover-jobs
-      - openstack-lower-constraints-jobs
       - openstack-python3-zed-jobs
       - periodic-stable-jobs
       - publish-openstack-docs-pti

lower-constraints.txt

@@ -1,92 +0,0 @@
-alembic==0.9.8
-# only need to speed up the pip version resolution
-amqp==2.5.0
-appdirs==1.4.3
-attrs==17.4.0
-bandit==1.1.0
-colorama==0.3.9
-coverage==4.0
-cryptography==2.7
-debtcollector==1.19.0
-decorator==4.0.0
-extras==1.0.0
-fasteners==0.14.1
-fixtures==3.0.0
-future==0.16.0
-gabbi==1.35.0
-gitdb2==2.0.3
-GitPython==2.1.8
-hacking==4.0.0
-iso8601==0.1.11
-Jinja2==2.10
-jsonpath-rw==1.4.0
-jsonpath-rw-ext==1.1.3
-jsonschema==3.2.0
-keystoneauth1==3.9.0
-keystonemiddleware==4.18.0
-linecache2==1.0.0
-Mako==1.0.7
-MarkupSafe==1.1.1
-microversion-parse==0.2.1
-monotonic==1.4
-mox3==0.20.0
-msgpack-python==0.5.6
-netaddr==0.7.18
-netifaces==0.10.4
-os-client-config==1.29.0
-os-resource-classes==1.1.0
-os-service-types==1.2.0
-os-traits==2.7.0
-oslo.concurrency==3.26.0
-oslo.config==6.7.0
-oslo.context==2.22.0
-oslo.db==8.6.0
-oslo.i18n==3.20.0
-oslo.log==4.3.0
-oslo.middleware==3.31.0
-oslo.policy==3.7.0
-oslo.serialization==2.25.0
-oslo.upgradecheck==1.3.0
-oslo.utils==4.5.0
-oslotest==3.5.0
-osprofiler==1.4.0
-pbr==3.1.1
-pep8==1.5.7
-pluggy==0.6.0
-ply==3.11
-prettytable==0.7.1
-psycopg2==2.8
-py==1.5.2
-pycadf==2.7.0
-PyMySQL==0.8.0
-pyparsing==2.2.0
-pytest==3.4.2
-python-dateutil==2.7.0
-python-editor==1.0.3
-python-keystoneclient==3.15.0
-python-mimeparse==1.6.0
-python-subunit==1.2.0
-pytz==2018.3
-PyYAML==5.1
-repoze.lru==0.7
-requests==2.25.0
-requestsexceptions==1.4.0
-rfc3986==0.3.1
-Routes==2.3.1
-smmap2==2.0.3
-SQLAlchemy==1.4.0
-setuptools==21.0.0
-sqlparse==0.2.4
-statsd==3.2.2
-stestr==1.0.0
-stevedore==1.20.0
-Tempita==0.5.2
-testrepository==0.0.20
-testresources==2.0.0
-testscenarios==0.4
-testtools==2.2.0
-traceback2==1.4.0
-unittest2==1.1.0
-WebOb==1.8.2
-wrapt==1.10.11
-wsgi-intercept==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

@@ -179,19 +179,3 @@ usedevelop = False
 deps = bindep
 commands =
   bindep test
-
-[testenv:lower-constraints]
-# When using pbr and in a git repo, 'setup.py install' does not install
-# packages. 'setup.py develop', used when usedevelop is True, does.
-usedevelop = False
-# Use our own install_command to turn off upper constraints, which conflicts
-# with lower constraints.
-install_command = pip install {opts} {packages}
-deps =
-  -c{toxinidir}/lower-constraints.txt
-  -r{toxinidir}/test-requirements.txt
-  -r{toxinidir}/requirements.txt
-# Test with both functional and unit tests.
-commands =
-  {[testenv]commands}
-  stestr --test-path=./placement/tests run {posargs}