Add metrics-reporter-prometheus plugin to the checks pipeline

Change-Id: Ia7464ad1d0169813ea82f23ffba8ecae539fabce

zuul.d/projects.yaml

diff --git a/zuul.d/projects.yaml b/zuul.d/projects.yaml
index 478004d..f0e4abc 100644
--- a/zuul.d/projects.yaml
+++ b/zuul.d/projects.yaml
@@ -183,6 +183,12 @@
         - gerrit-plugin-build
 
 - project:
+    name: plugins/metrics-reporter-prometheus
+    check:
+      jobs:
+        - gerrit-plugin-build
+
+- project:
     name: plugins/oauth
     check:
       jobs: