Make CentOS 9 integration jobs voting

RDO is releasing Yoga release for both CentOS 8 and CentOS 9, let's
ensure our modules works with both CentOS 8 and CentOS 9. Integration
jobs were added a while ago but these jobs have been constantly passing
without any issue.

Change-Id: Ife8fb4231e5b342e3ecf1d8da60cb7cbdf9d2840

zuul.d/integration.yaml

@@ -71,7 +71,6 @@
 - job:
     name: puppet-openstack-integration-7-scenario001-tempest-centos-9-stream
     parent: puppet-openstack-integration-7-scenario001
-    voting: false
     nodeset:
       nodes:
         - name: centos-9-stream
@@ -105,7 +104,6 @@
 - job:
     name: puppet-openstack-integration-7-scenario002-tempest-centos-9-stream
     parent: puppet-openstack-integration-7-scenario002
-    voting: false
     nodeset:
       nodes:
         - name: centos-9-stream
@@ -139,7 +137,6 @@
 - job:
     name: puppet-openstack-integration-7-scenario003-tempest-centos-9-stream
     parent: puppet-openstack-integration-7-scenario003
-    voting: false
     nodeset:
       nodes:
         - name: centos-9-stream
@@ -175,7 +172,6 @@
 - job:
     name: puppet-openstack-integration-7-scenario004-tempest-centos-9-stream
     parent: puppet-openstack-integration-7-scenario004
-    voting: false
     nodeset:
       nodes:
         - name: centos-9-stream