Add rate limiting for backup

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

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

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

First reconcile the title's request for backup rate limiting with the body’s request for helper filtering. Locate the configuration handling and the helper or backup entry points, then determine how `enable_filtering` should affect them and what production-deployment behavior is expected. Done means the intended filtering behavior, default-disabled configuration, and relevant verification are defined.

Written by the indexing model from the issue text.