Fixed wrong lazy loading of legacy kernel in IO\Handler\Legacy

This leads to weird exception message (*No security token found*) when IO handler is loaded early in the request, which is the case when we load the current user (user class has an `ezimage` field type).

The *No security token found* can be triggered because when the legacy kernel is booted and multi site is activated with a non-existing locationId. A generic `NotFoundException` is fired and caught in the user provider.

This PR fixes this side effect.