Build find-owners plugin on stable-3.4 branch

Change-Id: I7b1d5317ead95f20cfde0f9c7df9b9d7a97214c3
diff --git a/jenkins/gerrit-bazel-plugin-find-owners.yaml b/jenkins/gerrit-bazel-plugin-find-owners.yaml
index cf281ac..6cb865a 100644
--- a/jenkins/gerrit-bazel-plugin-find-owners.yaml
+++ b/jenkins/gerrit-bazel-plugin-find-owners.yaml
@@ -5,6 +5,7 @@
           branch:
             - master
           gerrit-branch:
+            - stable-3.4
             - stable-3.3
       - 'plugin-{name}-bazel-{branch}':
           branch: