zuul: Use default python3 job template

Skyline should use the default template openstack-python3-jobs which
will be updated each cycle according to the PTI.

Drop the py38 jobs, the current tested python versions are 3.9 and 3.11.
Also drop the irrelevant-files lists, the unit tests should run fast
enough that this doesn't really matter and this way we don't have to
update the config once new python versions get tested.

Change-Id: I5e9da608e5b277110b77ca5e6378855046798cf8

.zuul.yaml

@@ -25,40 +25,13 @@
         tox_install_siblings: false
         tox_envlist: functional
 
-- job:
-    name: skyline-tox-py38
-    parent: openstack-tox-py38
-    description: |
-      Skyline py38 unittest tests
-    vars:
-      python_version: 3.8
-      tox_envlist: py38
-
-- job:
-    name: skyline-tox-pep8-py38
-    parent: openstack-tox-py38
-    description: |
-      Skyline code static analysis
-    vars:
-      python_version: 3.8
-      tox_envlist: pep8
-
 - project:
     templates:
+      - openstack-python3-jobs
       - release-notes-jobs-python3
       - publish-openstack-docs-pti
     check:
       jobs:
-        - skyline-tox-py38:
-            irrelevant-files:
-              - ^container/.*$
-              - ^devstack/.*$
-              - ^docs/.*$
-              - ^tools/.*$
-              - ^.*\.rst$
-              - ^.*\.md$
-              - ^kolla/.*$
-        - skyline-tox-pep8-py38
         - skyline-functional-devstack:
             irrelevant-files:
               - ^container/.*$
@@ -71,16 +44,6 @@
               - ^releasenotes/.*$
     gate:
       jobs:
-        - skyline-tox-py38:
-            irrelevant-files:
-              - ^container/.*$
-              - ^devstack/.*$
-              - ^docs/.*$
-              - ^tools/.*$
-              - ^.*\.rst$
-              - ^.*\.md$
-              - ^kolla/.*$
-        - skyline-tox-pep8-py38
         - skyline-functional-devstack:
             irrelevant-files:
               - ^container/.*$