Build out-of-the-box plugin on stable-3.4

Change-Id: I0fdfa2f9a97b48d57f76af26fecf9fa9fd5d03c7
diff --git a/jenkins/gerrit-bazel-plugin-out-of-the-box.yaml b/jenkins/gerrit-bazel-plugin-out-of-the-box.yaml
index 10915fb..ce743e3 100644
--- a/jenkins/gerrit-bazel-plugin-out-of-the-box.yaml
+++ b/jenkins/gerrit-bazel-plugin-out-of-the-box.yaml
@@ -6,6 +6,7 @@
             - master
           gerrit-branch:
             - master
+            - stable-3.4
             - stable-3.3
             - stable-3.2
             - stable-3.1