networking-midonet: Make centos-7 job non-voting

Because these days it's failing too frequently due to
a problem which is seemingly unrelated to the code in this repo.
(maybe an infra issue)

Related-Bug: #1728602
Change-Id: I475a0cb7760b245d20776d54fd16ed9905af8f01

zuul.d/projects.yaml

@@ -13033,6 +13033,7 @@
               - ^setup.cfg$
               - ^specs/.*$
         - legacy-tempest-dsvm-networking-midonet-aio-ml2-centos-7:
+            voting: false
             irrelevant-files:
               - ^(test-|)requirements.txt$
               - ^.*\.rst$
@@ -13148,14 +13149,6 @@
               - ^midonet/neutron/tests/unit/.*$
               - ^setup.cfg$
               - ^specs/.*$
-        - legacy-tempest-dsvm-networking-midonet-aio-ml2-centos-7:
-            irrelevant-files:
-              - ^(test-|)requirements.txt$
-              - ^.*\.rst$
-              - ^doc/.*$
-              - ^midonet/neutron/tests/unit/.*$
-              - ^setup.cfg$
-              - ^specs/.*$
         - legacy-grenade-dsvm-networking-midonet-ml2:
             irrelevant-files:
               - ^(test-|)requirements.txt$