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: I38a41071ac540e3b58f9d18ead88b86203a4c843

.zuul.yaml

@@ -159,7 +159,6 @@
 - project:
     templates:
       - check-requirements
-      - openstack-lower-constraints-jobs
       - openstack-python3-zed-jobs
       - publish-openstack-docs-pti
       - release-notes-jobs-python3

lower-constraints.txt

@@ -1,22 +0,0 @@
-# from requirements.txt
-
-pbr==2.0.0
-netaddr==0.7.18
-oslo.concurrency==3.20.0
-oslo.config==5.1.0
-oslo.log==3.30.0
-oslo.i18n==3.15.3
-oslo.privsep==1.23.0
-oslo.versionedobjects==1.28.0
-ovsdbapp==0.12.1
-pyroute2==0.5.2;sys_platform!='win32'
-stevedore==1.20.0
-debtcollector==1.19.0
-
-# from test-requirements.txt
-
-coverage==4.0
-oslotest==1.10.0
-ovs==2.9.2
-stestr==1.0.0
-testscenarios==0.4

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

@@ -1,6 +1,6 @@
 [tox]
 minversion = 3.18.0
-envlist = py3,pep8,docs,releasenotes,cover,lower-constraints
+envlist = py3,pep8,docs,releasenotes,cover
 skipsdist = True
 ignore_basepython_conflict = True
 
@@ -43,16 +43,6 @@ envdir = {toxworkdir}/docs
 deps = {[testenv:docs]deps}
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
-[testenv:lower-constraints]
-deps =
-  -c{toxinidir}/lower-constraints.txt
-  -r{toxinidir}/requirements.txt
-  -r{toxinidir}/test-requirements.txt
-  -r{toxinidir}/doc/requirements.txt
-commands =
-  stestr run --black-regex ".tests.functional" {posargs}
-  sphinx-build -W doc/source doc/build
-
 [testenv:venv]
 commands = {posargs}
 deps =