Build metrics-reporter-prometheus for stable-3.0

Change-Id: Icab379da4ae71187675e7991fa95fbc9dd61e489
diff --git a/jenkins/gerrit-bazel-plugin-metrics-reporter-prometheus.yaml b/jenkins/gerrit-bazel-plugin-metrics-reporter-prometheus.yaml
index afe5692..b170cee 100644
--- a/jenkins/gerrit-bazel-plugin-metrics-reporter-prometheus.yaml
+++ b/jenkins/gerrit-bazel-plugin-metrics-reporter-prometheus.yaml
@@ -1,9 +1,14 @@
 - project:
     name: metrics-reporter-prometheus
     jobs:
-      - 'plugin-{name}-bazel-{branch}':
+      - 'plugin-{name}-bazel-{branch}-{gerrit-branch}':
           branch:
             - master
+          gerrit-branch:
+            - master
+            - stable-3.0
+      - 'plugin-{name}-bazel-{branch}':
+          branch:
             - stable-2.16
             - stable-2.15
             - stable-2.14