Add rate limiting for notifications

**Feature request**
It would be great to have filtering for utils.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_filtering` with default `false`.

Start by locating the notification and utils entry points, then find how configuration options are defined and tested. Clarify whether the intended change is notification rate limiting or generic utility filtering, since the title and body differ. Done should include the agreed behavior and an `enable_filtering` option whose default is `false`.

Written by the indexing model from the issue text.