Fix the path for Prometheus metrics

Change-Id: I13b2a8eb259841216aa7fe40e07f68202c71281b
diff --git a/jenkins/meta/prometheus.yml b/jenkins/meta/prometheus.yml
index c7384e6..b2ba5c5 100644
--- a/jenkins/meta/prometheus.yml
+++ b/jenkins/meta/prometheus.yml
@@ -4,7 +4,7 @@
   target:
     static:
       jenkins:
-        metrics_path: /prometheus
+        metrics_path: /prometheus/
         endpoint:
           - address: {{ client.master.host }}
             port: {{ client.master.port }}