Update websession-broker build

Build websession-broker 3.4 and 3.5 against gerrit stable-3.4 and
stable-3.5 respectively.

Change-Id: Id82b11a63add327e6cbae06e020de52110946ac7
diff --git a/jenkins/gerrit-bazel-plugin-websession-broker.yaml b/jenkins/gerrit-bazel-plugin-websession-broker.yaml
index ba63b4f..315d71a 100644
--- a/jenkins/gerrit-bazel-plugin-websession-broker.yaml
+++ b/jenkins/gerrit-bazel-plugin-websession-broker.yaml
@@ -7,8 +7,8 @@
           gerrit-branch:
             - master
             - stable-3.6
-            - stable-3.5
-            - stable-3.4
       - 'plugin-{name}-bazel-{branch}':
           branch:
+            - stable-3.5
+            - stable-3.4
             - stable-3.3