move ability check from service class to view

app/views/search/_category.html.haml

@@ -100,8 +100,9 @@
             Wiki
             %span.badge.badge-pill
               = limited_count(@search_results.wiki_blobs_count)
-      %li{ class: active_when(@scope == 'users') }
-        = link_to search_filter_path(scope: 'users') do
-          Users
-          %span.badge.badge-pill
-            = limited_count(@search_results.limited_users_count)
+      - if can?(current_user, :read_users_list)
+        %li{ class: active_when(@scope == 'users') }
+          = link_to search_filter_path(scope: 'users') do
+            Users
+            %span.badge.badge-pill
+              = limited_count(@search_results.limited_users_count)

lib/gitlab/search_results.rb

@@ -138,8 +138,6 @@ def merge_requests
     # rubocop: enable CodeReuse/ActiveRecord
 
     def users
-      return [] unless Ability.allowed?(current_user, :read_users_list)
-
       UsersFinder.new(current_user, search: query).execute
     end
 

spec/lib/gitlab/search_results_spec.rb

@@ -123,10 +123,6 @@
     end
 
     describe '#users' do
-      it 'returns an empty array when the current_user is not allowed to read users list' do
-        expect(results.objects('users')).to be_empty
-      end
-
       it 'calls the UsersFinder' do
         expect(UsersFinder).to receive(:new).with(user, search: 'foo').and_call_original