Consider deprecating old validation API

**Feature request**
It would be great to have timeout for core.

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

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

First reconcile the title's reference to deprecating the old validation API with the body’s request for a core timeout. Identify the core configuration entry point and existing configuration tests, then define the expected behavior of enable_timeout, including what timeout it controls and how the default false setting is verified.

Written by the indexing model from the issue text.