Avoid hard coding the refs/meta/config ref

Instead use it from RefNames.

Change-Id: I3446a4fc77eaa7682caa9a661b4e68e9f86ffe15

src/main/java/com/googlesource/gerrit/plugins/task/TaskConfigFactory.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/task/TaskConfigFactory.java b/src/main/java/com/googlesource/gerrit/plugins/task/TaskConfigFactory.java
index eee0999..b309dd4 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/task/TaskConfigFactory.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/task/TaskConfigFactory.java
@@ -18,6 +18,7 @@
 import com.google.gerrit.extensions.restapi.AuthException;
 import com.google.gerrit.reviewdb.client.Branch;
 import com.google.gerrit.reviewdb.client.Project;
+import com.google.gerrit.reviewdb.client.RefNames;
 import com.google.gerrit.server.CurrentUser;
 import com.google.gerrit.server.config.AllProjectsName;
 import com.google.gerrit.server.config.AllProjectsNameProvider;
@@ -69,7 +70,7 @@
   }
 
   protected Branch.NameKey getRootBranch() {
-    return new Branch.NameKey(allProjects, "refs/meta/config");
+    return new Branch.NameKey(allProjects, RefNames.REFS_CONFIG);
   }
 
   public TaskConfig getTaskConfig(FileKey key) throws ConfigInvalidException, IOException {