Fix comments related to BE part

- Edit commit messge body to fix "danger-review"

app/serializers/merge_request_sidebar_basic_entity.rb

@@ -1,6 +1,9 @@
 # frozen_string_literal: true
 
 class MergeRequestSidebarBasicEntity < IssuableSidebarBasicEntity
+  expose :current_user, if: lambda { |_issuable| current_user } do
+    expose :can_merge do |merge_request|
+      merge_request.can_be_merged_by?(current_user)
+    end
+  end
 end
-
-MergeRequestSidebarBasicEntity.prepend_if_ee('EE::MergeRequestSidebarBasicEntity')

spec/fixtures/api/schemas/entities/merge_request_sidebar.json

@@ -2,6 +2,7 @@
   "type": "object",
   "properties" : {
     "id": { "type": "integer" },
+    "iid": { "type": "integer" },
     "type": { "type": "string" },
     "author_id": { "type": "integer" },
     "project_id": { "type": "integer" },