Update Zuul queue configuration

Zuul is changing how queues are declared[1]

[1] https://lists.zuul-ci.org/pipermail/zuul-discuss/2022-May/001801.html

Also,
- fixing tox.ini as per the tox4
- remove stable branch testing which are in EM state

Change-Id: I1ffb896e0d30b4162e3c22f13462477feb4acba4

.zuul.yaml

@@ -90,10 +90,8 @@
         - mistral-devstack-kombu:
             branches: ^(?!stable/newton).*$
         - mistral-devstack-ussuri
-        - mistral-devstack-train
-        - mistral-devstack-stein
+    queue: mistral
     gate:
-      queue: mistral
       jobs:
         - mistral-devstack
         - mistral-devstack-tempest-ipv6-only
@@ -106,21 +104,3 @@
     parent: mistral-devstack
     nodeset: openstack-single-node-bionic
     override-checkout: stable/ussuri
-
-- job:
-    name: mistral-devstack-train
-    parent: mistral-devstack
-    nodeset: openstack-single-node-bionic
-    override-checkout: stable/train
-    vars:
-      devstack_localrc:
-        USE_PYTHON3: True
-
-- job:
-    name: mistral-devstack-stein
-    parent: mistral-devstack
-    override-checkout: stable/stein
-    nodeset: openstack-single-node-bionic
-    vars:
-      devstack_localrc:
-        USE_PYTHON3: True

tox.ini

@@ -1,7 +1,6 @@
 [tox]
 minversion = 3.1.1
 envlist = py3,pep8
-skipsdist = True
 ignore_basepython_conflict = True
 
 [testenv]
@@ -35,14 +34,14 @@ commands =
 
 [testenv:docs]
 deps = -r{toxinidir}/doc/requirements.txt
-whitelist_externals =
+Allowlist_externals =
   rm
 commands =
   rm -fr doc/build
   sphinx-build -E -W --keep-going -b html doc/source doc/build/html
 
 [testenv:releasenotes]
-whitelist_externals =
+Allowlist_externals =
   rm
 commands =
   rm -rf releasenotes/build