Drop lower-constraints

Per a general OpenStack resolution [1], lower-constraints
are not worth the extra work and confusion they introduce.
This patch drops them along with all mentions.

[1] http://lists.openstack.org/pipermail/openstack-discuss/2020-December/019521.html

Change-Id: I7d1595c1dc3eb834f3b13b11f608b90aaff1d349

.zuul.yaml

@@ -1,7 +1,6 @@
 - project:
     templates:
       - check-requirements
-      - openstack-lower-constraints-jobs
       - openstack-python3-wallaby-jobs
       - publish-openstack-docs-pti
       - release-notes-jobs-python3

lower-constraints.txt

@@ -1,102 +0,0 @@
-automaton==1.9.0
-alabaster==0.7.10
-appdirs==1.4.3
-asn1crypto==0.24.0
-certifi==2018.1.18
-cffi==1.14.0
-chardet==3.0.4
-cliff==2.11.0
-cmd2==0.8.1
-coverage==4.0
-cryptography==2.1.4
-ddt==1.0.1
-debtcollector==1.19.0
-decorator==4.2.1
-deprecation==2.0
-docutils==0.14
-dogpile.cache==0.6.5
-dulwich==0.19.0
-enum-compat==0.0.2
-eventlet==0.20.0
-extras==1.0.0
-fasteners==0.14.1
-fixtures==3.0.0
-future==0.16.0
-greenlet==0.4.13
-idna==2.6
-imagesize==1.0.0
-iso8601==0.1.12
-Jinja2==2.10
-jmespath==0.9.3
-jsonpatch==1.21
-jsonpointer==2.0
-jsonschema==2.6.0
-keystoneauth1==3.4.0
-libvirt-python==6.0.0
-linecache2==1.0.0
-MarkupSafe==1.1.1
-monotonic==1.4
-mox3==0.25.0
-msgpack==0.5.6
-munch==2.2.0
-netaddr==0.7.19
-netifaces==0.10.6
-lxml==4.5.0
-openstacksdk==0.13.0
-os-client-config==1.29.0
-os-service-types==1.2.0
-os-testr==1.0.0
-osc-lib==1.10.0
-oslo.cache==1.26.0
-oslo.concurrency==3.26.0
-oslo.config==5.2.0
-oslo.context==2.20.0
-oslo.i18n==3.15.3
-oslo.log==3.36.0
-oslo.middleware==3.31.0
-oslo.privsep==1.23.0
-oslo.serialization==2.25.0
-oslo.service==1.24.0
-oslo.utils==3.33.0
-oslotest==3.2.0
-packaging==17.1
-Paste==2.0.3
-PasteDeploy==1.5.2
-pbr==2.0.0
-prettytable==0.7.2
-pycparser==2.18
-Pygments==2.2.0
-pyinotify==0.9.6
-pyOpenSSL==17.5.0
-pyparsing==2.2.0
-pyperclip==1.6.0
-python-cinderclient==3.5.0
-python-dateutil==2.7.0
-python-glanceclient==2.9.1
-python-keystoneclient==3.15.0
-python-masakariclient==5.0.0
-python-mimeparse==1.6.0
-python-novaclient==10.1.0
-python-subunit==1.0.0
-pytz==2018.3
-PyYAML==3.13
-repoze.lru==0.7
-requests==2.18.4
-requestsexceptions==1.4.0
-rfc3986==1.1.0
-Routes==2.4.1
-simplejson==3.13.2
-snowballstemmer==1.2.1
-statsd==3.2.2
-stestr==2.0.0
-stevedore==1.28.0
-testrepository==0.0.18
-testscenarios==0.4
-testtools==2.2.0
-traceback2==1.4.0
-unittest2==1.1.0
-urllib3==1.22
-voluptuous==0.11.1
-warlock==1.3.0
-WebOb==1.7.4
-wrapt==1.10.11

tox.ini

@@ -74,12 +74,6 @@ extension =
     M304 = checks:assert_raisesRegexp
 paths = ./masakarimonitors/hacking
 
-[testenv:lower-constraints]
-deps =
-  -c{toxinidir}/lower-constraints.txt
-  -r{toxinidir}/test-requirements.txt
-  -r{toxinidir}/requirements.txt
-
 [testenv:bindep]
 # Do not install any requirements. We want this to be fast and work even if
 # system dependencies are missing, since it's used to tell you what system