Run plugin build job on core plugins

Core plugins do not need to build all of gerrit; bazel will build
whatever part of gerrit is required.  So changes to core plugin
repos should run the plugin-build job rather than the full
gerrit build.

Change-Id: Ibaa325242cf97d0c4102bd12f59851d4f7766bcf
diff --git a/zuul.d/projects.yaml b/zuul.d/projects.yaml
index 264f30f..c2f8184 100644
--- a/zuul.d/projects.yaml
+++ b/zuul.d/projects.yaml
@@ -10,64 +10,64 @@
     name: plugins/codemirror-editor
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build
 
 - project:
     name: plugins/commit-message-length-validator
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build
 
 - project:
     name: plugins/delete-project
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build
 
 - project:
     name: plugins/download-commands
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build
 
 - project:
     name: plugins/gitiles
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build
 
 - project:
     name: plugins/hooks
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build
 
 - project:
     name: plugins/plugin-manager
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build
 
 - project:
     name: plugins/replication
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build
 
 - project:
     name: plugins/reviewnotes
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build
 
 - project:
     name: plugins/singleusergroup
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build
 
 - project:
     name: plugins/webhooks
     check:
       jobs:
-        - gerrit-build
+        - gerrit-plugin-build