Simplify pipeline processing service

app/models/concerns/ci/processable.rb

@@ -16,10 +16,6 @@ module Ci
       raise NotImplementedError
     end
 
-    def artifacts?
-      raise NotImplementedError
-    end
-
     def when
       raise NotImplementedError
     end

app/services/ci/process_build_service.rb

@@ -9,7 +9,7 @@ module Ci
         elsif build.action?
           build.actionize
         else
-          enqueue(build)
+          build.enqueue
         end
 
         true
@@ -21,10 +21,6 @@ module Ci
 
     private
 
-    def enqueue(build)
-      build.enqueue
-    end
-
     def valid_statuses_for_when(value)
       case value
       when 'on_success'