Remove feature flag for using dashboard CTE

This has been running in production for a few months now without issues,
so we should be able to remove it now.

app/controllers/dashboard/projects_controller.rb

@@ -83,7 +83,7 @@ def preload_associations(projects)
 
   def use_cte_for_finder?
     # The starred action loads public projects, which causes the CTE to be less efficient
-    action_name == 'index' && Feature.enabled?(:use_cte_for_projects_finder, default_enabled: true)
+    action_name == 'index'
   end
 
   def load_events