Fixes #36329: Read UI notification cache as JSON

The UI notification data is cached as JSON and when retrieved needs
to also be JSON or else a marshalling error is thrown.

app/services/ui_notifications/cache_handler.rb

@@ -7,7 +7,7 @@ def initialize(user_id = User.current.try(:id))
 
     # JSON Payload
     def payload
-      result = cache.read(cache_key)
+      result = cache.read(cache_key, raw: true)
       if result
         logger.debug("Cache Hit: notification, reading cache for #{cache_key}")
         return result