[EE] Add users search results to global search

What does this MR do?

EE version of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21197

What are the relevant issue numbers?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?
• Security reports checked/validated by reviewer

app/controllers/search_controller.rb

@@ -29,6 +29,7 @@ class SearchController < ApplicationController
     @search_objects = search_service.search_objects
 
     render_commits if @scope == 'commits'
+    eager_load_user_status if @scope == 'users'
 
     check_single_commit_result
   end
@@ -54,6 +55,12 @@ class SearchController < ApplicationController
     @search_objects = prepare_commits_for_rendering(@search_objects)
   end
 
+  def eager_load_user_status
+    return if Feature.disabled?(:users_search, default_enabled: true)
+
+    @search_objects = @search_objects.eager_load(:status) # rubocop:disable CodeReuse/ActiveRecord
+  end
+
   def check_single_commit_result
     if @search_results.single_commit_result?
       only_commit = @search_results.objects('commits').first