Build metrics-* plugins for Gerrit v3.{1,2}

Change-Id: Ib269e0a2637b42c0c922aed09462df92c8a115f2
diff --git a/jenkins/gerrit-bazel-plugin-metrics-reporter-graphite.yaml b/jenkins/gerrit-bazel-plugin-metrics-reporter-graphite.yaml
index f2dba26..6b4a988 100644
--- a/jenkins/gerrit-bazel-plugin-metrics-reporter-graphite.yaml
+++ b/jenkins/gerrit-bazel-plugin-metrics-reporter-graphite.yaml
@@ -6,5 +6,7 @@
             - master
           gerrit-branch:
             - master
+            - stable-3.2
+            - stable-3.1
             - stable-3.0
             - stable-2.16
diff --git a/jenkins/gerrit-bazel-plugin-metrics-reporter-jmx.yaml b/jenkins/gerrit-bazel-plugin-metrics-reporter-jmx.yaml
index 520878f..1b4edf7 100644
--- a/jenkins/gerrit-bazel-plugin-metrics-reporter-jmx.yaml
+++ b/jenkins/gerrit-bazel-plugin-metrics-reporter-jmx.yaml
@@ -6,5 +6,7 @@
             - master
           gerrit-branch:
             - master
+            - stable-3.2
+            - stable-3.1
             - stable-3.0
             - stable-2.16
diff --git a/jenkins/gerrit-bazel-plugin-metrics-reporter-prometheus.yaml b/jenkins/gerrit-bazel-plugin-metrics-reporter-prometheus.yaml
index e53b908..ad23d05 100644
--- a/jenkins/gerrit-bazel-plugin-metrics-reporter-prometheus.yaml
+++ b/jenkins/gerrit-bazel-plugin-metrics-reporter-prometheus.yaml
@@ -6,6 +6,7 @@
             - master
           gerrit-branch:
             - master
+            - stable-3.2
             - stable-3.1
             - stable-3.0
       - 'plugin-{name}-bazel-{branch}':