Build zookeeper-refdb on stable-3.11

Change-Id: Ib0046d5f89d98ab3ae40a1d8a1ecec6b00595684
diff --git a/jenkins/gerrit-bazel-plugin-zookeeper-refdb.yaml b/jenkins/gerrit-bazel-plugin-zookeeper-refdb.yaml
index 8497783..246a9a4 100644
--- a/jenkins/gerrit-bazel-plugin-zookeeper-refdb.yaml
+++ b/jenkins/gerrit-bazel-plugin-zookeeper-refdb.yaml
@@ -11,6 +11,7 @@
           targets: "plugins/{name}:{name}"
           branch:
             - master
+            - stable-3.11
             - stable-3.10
             - stable-3.9
           extra-modules: 'global-refdb'