Build metrics-reporter-cloudwatch plugin on stable-3.4

Change-Id: I0b157b47f4d7305b99e8a761f0416463a3afff46
diff --git a/jenkins/gerrit-bazel-plugin-metrics-reporter-cloudwatch.yaml b/jenkins/gerrit-bazel-plugin-metrics-reporter-cloudwatch.yaml
index e69168e..082d859 100644
--- a/jenkins/gerrit-bazel-plugin-metrics-reporter-cloudwatch.yaml
+++ b/jenkins/gerrit-bazel-plugin-metrics-reporter-cloudwatch.yaml
@@ -6,3 +6,8 @@
             - master
             - stable-3.3
             - stable-3.2
+      - 'plugin-{name}-bazel-{branch}-{gerrit-branch}':
+          branch:
+            - master
+          gerrit-branch:
+            - stable-3.4