Move wiki statistics deletion to after_destroy

app/models/project.rb

@@ -85,8 +85,8 @@ class Project < ActiveRecord::Base
   after_create :create_project_feature, unless: :project_feature
 
   after_create -> { SiteStatistic.track(STATISTICS_ATTRIBUTE) }
-  before_destroy ->(project) { project.project_feature.untrack_statistics_for_deletion! }
-  after_destroy -> { SiteStatistic.untrack(STATISTICS_ATTRIBUTE) }
+  before_destroy ->(project) { project.project_feature } # keep reference so we can untrack later
+  after_destroy :untrack_site_statistics
 
   after_create :create_ci_cd_settings,
     unless: :ci_cd_settings,
@@ -2093,6 +2093,11 @@ class Project < ActiveRecord::Base
     Gitlab::PagesTransfer.new.rename_project(path_before, self.path, namespace.full_path)
   end
 
+  def untrack_site_statistics
+    SiteStatistic.untrack(STATISTICS_ATTRIBUTE)
+    SiteStatistic.project_feature.untrack_statistics_for_deletion!
+  end
+
   def execute_rename_repository_hooks!(full_path_before)
     # When we import a project overwriting the original project, there
     # is a move operation. In that case we don't want to send the instructions.