Moving query to base count service

app/services/projects/count_service.rb

@@ -11,6 +11,10 @@ module Projects
       @project = project
     end
 
+    def relation_for_count
+      self.class.query(@project.id)
+    end
+
     def cache_key_name
       raise(
         NotImplementedError,

app/services/projects/forks_count_service.rb

 module Projects
   # Service class for getting and caching the number of forks of a project.
   class ForksCountService < Projects::CountService
-    def relation_for_count
-      self.class.query(@project.id)
-    end
-
     def cache_key_name
       'forks_count'
     end

app/services/projects/open_issues_count_service.rb

@@ -2,10 +2,6 @@ module Projects
   # Service class for counting and caching the number of open issues of a
   # project.
   class OpenIssuesCountService < Projects::CountService
-    def relation_for_count
-      self.class.query(@project.id)
-    end
-
     def cache_key_name
       'open_issues_count'
     end