zuul: Declare queue at top level

Zuul deprecated declaring shared queues at a pipeline level with
release 4.1.0[1]. This updates the job definition to use the top level
declaration instead.

See [2] for details.

[1] https://zuul-ci.org/docs/zuul/latest/releasenotes.html#relnotes-4-1-0-deprecation-notes
[2] http://lists.openstack.org/pipermail/openstack-discuss/2022-May/028603.html

Change-Id: I46522cb94072d3c5d6f137187a7769ce05430c29

.zuul.yaml

@@ -49,6 +49,7 @@
     override-checkout: stable/wallaby
 
 - project:
+    queue: heat
     templates:
       - check-requirements
       - tempest-plugin-jobs
@@ -62,7 +63,6 @@
         - heat-functional-victoria
         - heat-functional-wallaby
     gate:
-      queue: heat
       jobs:
         - heat-functional
         - heat-functional-legacy