Merge branch 'fix-500-in-notes-polling' into 'master'

Fix notes polling failing after code changes

Closes #29327

See merge request !9862

lib/gitlab/etag_caching/middleware.rb

@@ -37,7 +37,7 @@ module Gitlab
 
       def get_etag(env)
         cache_key = env['PATH_INFO']
-        store = Store.new
+        store = Gitlab::EtagCaching::Store.new
         current_value = store.get(cache_key)
         cached_value_present = current_value.present?