Build menuextender plugin for Gerrit v3.{1,2}

Change-Id: Ib4d58f3556de778c1c0028afe1129800b19ab2a0
diff --git a/jenkins/gerrit-bazel-plugin-menuextender.yaml b/jenkins/gerrit-bazel-plugin-menuextender.yaml
index 511bc63..86b554f 100644
--- a/jenkins/gerrit-bazel-plugin-menuextender.yaml
+++ b/jenkins/gerrit-bazel-plugin-menuextender.yaml
@@ -6,5 +6,7 @@
             - master
           gerrit-branch:
             - master
+            - stable-3.2
+            - stable-3.1
             - stable-3.0
             - stable-2.16