trivial: Add hacking checks to irrelevant-files in .zuul.yaml

This is to skip over hacking modifications triggering all Patrole
Zuul jobs as in [0]. Besides, Tempest also skips hacking in its
irrelevant-files [1]. Also do this for etc/.

[0] https://review.openstack.org/#/c/614655/3
[1] da8aec9aed/.zuul.yaml (L326)

Change-Id: Iee5b634e77c2faaa36d3d19a3b56b1fec685aa7e

.zuul.yaml

@@ -14,7 +14,9 @@
       - ^(test-|)requirements.txt$
       - ^.*\.rst$
       - ^doc/.*
+      - ^etc/.*$
       - ^patrole/patrole_tempest_plugin/tests/unit/.*$
+      - ^patrole/patrole_tempest_plugin/hacking/.*$
       - ^releasenotes/.*
       - ^setup.cfg$
     vars:
@@ -50,7 +52,9 @@
       - ^(test-|)requirements.txt$
       - ^.*\.rst$
       - ^doc/.*
+      - ^etc/.*$
       - ^patrole/patrole_tempest_plugin/tests/unit/.*$
+      - ^patrole/patrole_tempest_plugin/hacking/.*$
       - ^releasenotes/.*
       - ^setup.cfg$
     vars: