Add rate limiting for monitoring

**Feature request**
It would be great to have import for handlers.

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

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

No files or tests are named. Start by tracing the monitoring configuration and handler-import entry points, then confirm the intended behavior for enable_import with its default set to false and establish how the change will be verified.

Written by the indexing model from the issue text.