CI: make Debian source jobs voting

We have Debian support for quite a while. While binary target is not
always up-to-date (due to Debian OpenStack team policy of building only
released code, not git snapshots) source images are expected to just
work.

Change-Id: I094c8559726d1068b65366ff86732881d3be5929

Author: hrw

.zuul.d/debian.yaml

@@ -9,6 +9,11 @@
       jobs:
         - kolla-build-debian-source-aarch64
         - kolla-ansible-debian-source-aarch64
+    gate:
+      queue: kolla
+      jobs:
+        - kolla-build-debian-source
+        - kolla-ansible-debian-source
     periodic:
       jobs:
         - kolla-publish-debian-source-quay
@@ -25,7 +30,6 @@
     name: kolla-build-debian-source
     parent: kolla-base
     nodeset: kolla-debian-bullseye
-    voting: false
     vars:
       base_distro: debian
       install_type: source