Make metal3 job voting

Now that we have autocommit disabled, we need to make the metal3 job
voting to ensure we don't accidentally break sqlite support in the
future.

Change-Id: I4915dc23b1101b9b799f392434f237e5ccb323e4

zuul.d/project.yaml

@@ -37,6 +37,7 @@
         - ironic-tempest-bfv
         - ironic-tempest-ipa-partition-uefi-pxe-grub2
         - metalsmith-integration-glance-centos8-legacy
+        - metal3-integration
         # Non-voting jobs
         - ironic-tox-bandit:
             voting: false
@@ -62,8 +63,6 @@
             voting: false
         - bifrost-benchmark-ironic:
             voting: false
-        - metal3-integration:
-            voting: false
     gate:
       jobs:
         - ironic-tox-unit-with-driver-libs
@@ -85,6 +84,7 @@
         - ironic-tempest-bfv
         - ironic-tempest-ipa-partition-uefi-pxe-grub2
         - metalsmith-integration-glance-centos8-legacy
+        - metal3-integration
     experimental:
       jobs:
         # TODO(dtantsur): these jobs are useful but currently hopelessly