Update zuul queue configuration

Zuul is changing how queues are declared[1]. This patch updates Designate tempest plugin for the new way to define the queue.

[1] https://lists.zuul-ci.org/pipermail/zuul-discuss/2022-May/001801.html

Change-Id: I0c50864a43df520d4213002656547d7b6b6d6775
diff --git a/.zuul.yaml b/.zuul.yaml
index 73a92ad..d40d786 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -26,5 +26,4 @@
         - designate-bind9-stable-xena
         - designate-bind9-stable-wallaby
         - neutron-tempest-plugin-designate-scenario
-    gate:
-      queue: designate
+    queue: designate