gate: Make swift-multinode-rolling-upgrade voting again

Change-Id: I04dc249365bbdb511b036c7f433778ff30285591
(cherry picked from commit 9ab9acb03f)

.zuul.yaml

@@ -598,7 +598,6 @@
               - ^doc/(requirements.txt|(saio|s3api|source)/.*)$
         - swift-multinode-rolling-upgrade:
             irrelevant-files: *functest-irrelevant-files
-            voting: false
         - tempest-integrated-object-storage:
             irrelevant-files: &tempest-irrelevant-files
               - ^(api-ref|doc|releasenotes)/.*$
@@ -642,6 +641,8 @@
             irrelevant-files: *unittest-irrelevant-files
         - openstack-tox-pep8:
             irrelevant-files: *pep8-irrelevant-files
+        - swift-multinode-rolling-upgrade:
+            irrelevant-files: *functest-irrelevant-files
         - tempest-integrated-object-storage:
             irrelevant-files: *tempest-irrelevant-files
         - tempest-ipv6-only: