Symfony version(s) affected: 4.2.5

Description
When I enable a circular reference handler in my framework.yaml, I get a deprecation warning in my logs

How to reproduce
Enable a circular reference handler in your framework.yaml:

serializer:
  enabled: true
  circular_reference_handler: Cbp\Utils\CircularReferenceHandler

Possible Solution
The FrameworkExtension reads the config, and calls setCircularReferenceHandler() on AbstractNormalizer, but instead it should set it as a default context.

Additional context