Use plain tox jobs instead of openstack ones

We want to be more flexible in terms of selecting which python versions
we test against. So replace the use of the openstack template with
explicit job invocations.

Change-Id: I2159e81d4a2fd46a83993b01bbea5fb37546ace5

.zuul.d/project.yaml

@@ -7,10 +7,21 @@
       # NOTE(ianw): 2020-05-29 jobs are unstable; see
       # https://bugs.launchpad.net/tripleo/+bug/1879766
       - tripleo-buildimage-jobs-centos-8
-      - openstack-python3-zed-jobs
     check:
       jobs:
         - openstack-tox-pylint
+        - tox-py36:
+            nodeset:
+              nodes:
+                - name: ubuntu-bionic
+                  label: ubuntu-bionic
+        - tox-py38
+        - tox-py39
+        - tox-py310:
+            nodeset:
+              nodes:
+                - name: ubuntu-jammy
+                  label: ubuntu-jammy
         - dib-functests
         - opendev-buildset-registry
         - nodepool-build-image-siblings
@@ -45,6 +56,18 @@
     gate:
       jobs:
         - openstack-tox-pylint
+        - tox-py36:
+            nodeset:
+              nodes:
+                - name: ubuntu-bionic
+                  label: ubuntu-bionic
+        - tox-py38
+        - tox-py39
+        - tox-py310:
+            nodeset:
+              nodes:
+                - name: ubuntu-jammy
+                  label: ubuntu-jammy
         - opendev-buildset-registry
         - nodepool-build-image-siblings
         - dib-nodepool-functional-openstack-centos-7-src