Zuul: Move jobs to bullseye node

importlib_metadata, a dependency for building python pkgs,
received changes where some of its API is deprecated [1],
causing the error:

AttributeError: 'EntryPoints' object has no attribute 'get'

A possible fix is to clip the version to below 5.0,
but the debian-bullseye Zuul node already provides a compatible
version, with the added advantage of being the base OS
used for STX, increasing reliability for the tests.

Refs:
[1] https://importlib-metadata.readthedocs.io/en/latest/history.html#v5-0-0

Test Plan:
pass - Run tox tests in a debian:bullseye container

Partial-Bug: 2090865

Change-Id: If86a054b741b11cb1aba08f85a9da8c5770b99d9
Signed-off-by: Leonardo Fagundes Luz Serrano <Leonardo.FagundesLuzSerrano@windriver.com>

.zuul.yaml

@@ -8,20 +8,34 @@
       - stx-bandit-jobs
     check:
       jobs:
-        - openstack-tox-linters
-        - openstack-tox-pep8
+        - fault-tox-linters
+        - fault-tox-pep8
         - fault-tox-pylint
         - fault-rest-api-py39
     gate:
       jobs:
-        - openstack-tox-linters
-        - openstack-tox-pep8
+        - fault-tox-linters
+        - fault-tox-pep8
         - fault-tox-pylint
         - fault-rest-api-py39
     post:
       jobs:
         - stx-fault-upload-git-mirror
 
+- job:
+    name: fault-tox-linters
+    parent: openstack-tox-linters
+    description: |
+      Run tox linters on specific nodeset
+    nodeset: debian-bullseye
+
+- job:
+    name: fault-tox-pep8
+    parent: openstack-tox-pep8
+    description: |
+      Run pep8 tests (flake8) on specific nodeset
+    nodeset: debian-bullseye
+
 - job:
     name: fault-rest-api-py39
     parent: tox-py39