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: I286e2ec118ad1c22018187e3ae7d7093bf342696

.zuul.yaml

@@ -1,7 +1,6 @@
 - project:
     templates:
       - check-requirements
-      - openstack-lower-constraints-jobs
       - openstack-python3-yoga-jobs
       - openstack-python3-xena-jobs-arm64
       - publish-openstack-docs-pti

lower-constraints.txt

@@ -1,43 +0,0 @@
-alabaster==0.7.10
-astroid==2.1.0
-Babel==2.3.4
-cliff==2.8.0
-cmd2==0.8.0
-coverage==4.5.1
-debtcollector==1.2.0
-docutils==0.11
-dulwich==0.15.0
-extras==1.0.0
-fixtures==3.0.0
-imagesize==0.7.1
-iso8601==0.1.11
-Jinja2==2.10
-keystoneauth1==3.4.0
-linecache2==1.0.0
-logilab-common==1.4.1
-MarkupSafe==1.1.1
-monotonic==0.6
-netaddr==0.7.18
-netifaces==0.10.4
-oslo.i18n==3.15.3
-oslo.serialization==2.25.0
-oslo.utils==3.33.0
-pbr==2.0.0
-prettytable==0.7.2
-Pygments==2.2.0
-pylint==2.2.0
-pyparsing==2.1.0
-pyperclip==1.5.27
-python-mimeparse==1.6.0
-python-subunit==1.0.0
-pytz==2013.6
-PyYAML==3.13
-requests==2.14.2
-setuptools==21.0.0
-snowballstemmer==1.2.1
-stevedore==1.20.0
-stestr==2.0.0
-testtools==2.2.0
-traceback2==1.4.0
-unittest2==1.1.0
-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

@@ -77,9 +77,3 @@ deps =
     -r{toxinidir}/requirements.txt
     -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -a -E -d releasenotes/build/doctrees -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