Symfony version(s) affected: 4.4.0

Description
When add the annotation @Assert\DisableAutoMapping(), the Validator component try to find the DisableAutoMappingValidator class, but it doesn't exists. Then you have a 500 error.

How to reproduce
In validator.yaml, under farmework -> validation, add:

#auto_mapping:
#    App\Entity\: []

Then, in an entity add the special @Assert\DisableAutoMapping(). On the next validation, the Validator try to find the DisableAutoMappingValidator and fail.

Possible Solution
At the moment in my case, I've just create the Validator with a return in the validate method. Because, the Assert is not use as a Validator by the Validator component. But, this is apparently the Bridge/Doctrine/Validator/DoctrineLoader that take care of this annotations.

<?php

namespace Symfony\Component\Validator\Constraints;

use Symfony\Component\Validator\Constraint;
use Symfony\Component\Validator\ConstraintValidator;
use Symfony\Component\Validator\Exception\UnexpectedTypeException;
use Symfony\Component\Validator\Exception\UnexpectedValueException;

class DisableAutoMappingValidator extends ConstraintValidator
{
    public function validate($value, Constraint $constraint)
    {
        return;
    }
}

But there is maybe a better solution ? Else, I've a PR (https://github.com/mpiot/symfony/tree/auto_mapping)

Additional context

Constraint validator "Symfony\Component\Validator\Constraints\DisableAutoMappingValidator" does not exist or is not enabled. Check the "validatedBy" method in your constraint class "Symfony\Component\Validator\Constraints\DisableAutoMapping".