Remove duplicated irrelevant-files for sanity check

This commit removes duplicated irrelevant-files for sanity-check in the
job definition. We have the same entries in the later. So we can remove
the redundancy.

Change-Id: I11e2054758fb9d4292e7cc64b58017c3e462c939

.zuul.yaml

@@ -454,13 +454,6 @@
       tox_envlist: plugin-sanity-check
     voting: false
     timeout: 5000
-    irrelevant-files:
-      - ^.*\.rst$
-      - ^doc/.*$
-      - ^etc/.*$
-      - ^releasenotes/.*$
-      - ^tempest/hacking/.*$
-      - ^tempest/tests/.*$
     required-projects:
       - opendev.org/airship/tempest-plugin
       - opendev.org/x/almanach