Build high-availability plugin on stable-3.4 branch

Change-Id: Ia33e03260d05c888ad1f9763240d433e750898fd
diff --git a/jenkins/gerrit-bazel-plugin-high-availability.yaml b/jenkins/gerrit-bazel-plugin-high-availability.yaml
index d960742..d104400 100644
--- a/jenkins/gerrit-bazel-plugin-high-availability.yaml
+++ b/jenkins/gerrit-bazel-plugin-high-availability.yaml
@@ -10,4 +10,9 @@
             - stable-2.16
             - stable-2.15
             - stable-2.14
+      - 'plugin-{name}-bazel-{branch}-{gerrit-branch}':
+          branch:
+            - master
+          gerrit-branch:
+            - stable-3.4
       - plugin-{name}-verifier