Add a shared openstack-tox-pylint job

There are many legacy-*-pylint jobs which are just wrappers to the
pylint tox environment, so define a shared job for them.

Change-Id: I71f7d6c0275b5f685b6b3b508ff1908c616ceae3

zuul.d/jobs.yaml

@@ -310,6 +310,20 @@
     vars:
       tox_envlist: validate
 
+- job:
+    name: openstack-tox-pylint
+    parent: openstack-tox
+    description: |
+      Runs pylint tests.
+
+      Uses tox with the ``pylint`` environment.
+    irrelevant-files:
+      - ^.*\.rst$
+      - ^doc/.*$
+      - ^releasenotes/.*$
+    vars:
+      tox_envlist: pylint
+
 - job:
     name: openstack-tox-compare-cover
     parent: openstack-tox