Build the batch plugin for stable-2.16

Change-Id: I89d49e9ac9ef3eff8de6361d9afa308b06580ae2
diff --git a/jenkins/gerrit-bazel-plugin-batch.yaml b/jenkins/gerrit-bazel-plugin-batch.yaml
index 71d3f01..60e0326 100644
--- a/jenkins/gerrit-bazel-plugin-batch.yaml
+++ b/jenkins/gerrit-bazel-plugin-batch.yaml
@@ -4,4 +4,5 @@
       - 'plugin-{name}-bazel-{branch}':
           branch:
             - master
+            - stable-2.16
             - stable-2.15