Store projects in metrics for email replies

lib/gitlab/email/handler/create_note_handler.rb

@@ -7,6 +7,8 @@ module Gitlab
       class CreateNoteHandler < BaseHandler
         include ReplyProcessing
 
+        delegate :project, to: :sent_notification, allow_nil: true
+
         def can_handle?
           mail_key =~ /\A\w+\z/
         end
@@ -32,10 +34,6 @@ module Gitlab
           sent_notification.recipient
         end
 
-        def project
-          sent_notification.project
-        end
-
         def sent_notification
           @sent_notification ||= SentNotification.for(mail_key)
         end

lib/gitlab/email/handler/unsubscribe_handler.rb

@@ -4,6 +4,8 @@ module Gitlab
   module Email
     module Handler
       class UnsubscribeHandler < BaseHandler
+        delegate :project, to: :sent_notification, allow_nil: true
+
         def can_handle?
           mail_key =~ /\A\w+#{Regexp.escape(Gitlab::IncomingEmail::UNSUBSCRIBE_SUFFIX)}\z/
         end