Symfony version(s) affected: 4.2.8

Description
doctrine-bridge uses symfony-form in require-dev.
However, during cache:clear in non-dev mode it does load Form/DoctrineOrmTypeGuesser.php which implements FormTypeGuesserInterface.
The interface FormTypeGuesserInterface can not be found if symfony/form is not installed.

PHP <7.2.0 allowed for such scenario (see https://bugs.php.net/bug.php?id=76980). Starting at PHP 7.2.0 a fatal error is thrown.

How to reproduce

• Install PHP 7.2.0
• require symfony/doctrine-bridge in composer.json
• run 'composer install'

Possible Solution
Move symfony/form from require-dev to require

Additional context
Output :

• Configuring symfony/security-bundle (>=3.3): From github.com/symfony/recipes:master
• Configuring symfony/validator (>=4.1): From github.com/symfony/recipes:master
  Executing script cache:clear [KO]
  [KO]
  Script cache:clear returned with error code 255
  !!
  !! // Clearing the cache for the prod environment with debug
  !! // false
  !!
  !! PHP Fatal error: During class fetch: Uncaught ReflectionException: Class Symfony\Component\Form\FormTypeGuesserInterface not found in /opt/releases/20190626075527/api/vendor/symfony/doctrine-bridge/Form/DoctrineOrmTypeGuesser.php:25
  !! Stack trace:
  !! #0 /opt/releases/20190626075527/api/vendor/composer/ClassLoader.php(444): include('/opt/releases/2...')
  !! Untitled #1 /opt/releases/20190626075527/api/vendor/composer/ClassLoader.php(322): Composer\Autoload\includeFile('/opt/releases/2...')
  !! Renaming "Entities" to "Entity" #2 [internal function]: Composer\Autoload\ClassLoader->loadClass('Symfony\Bridge\...')
  !! Untitled #3 [internal function]: spl_autoload_call('Symfony\Bridge\...')
  !! Same change for mapping files #4 /opt/releases/20190626075527/api/vendor/symfony/config/Resource/ClassExistenceResource.php(76): class_exists('Symfony\Bridge\...')
  !! Using ORM and MongoDB both in the same bundle. #5 /opt/releases/20190626075527/api/vendor/symfony/dependency-injection/ContainerBuilder.php(353): Symfony\Component\Config\Resource\ClassExistenceResource->isFresh(0)
  !! [Form] Outstanding patches for Choice/Collection fields #6 /opt/releases/20190626075527/api/vendor/symfony/dependency-injection/Compiler/AutowirePass.php(338): Sy in /opt/releases/20190626075527/api/vendor/symfony/doctrine-bridge/Form/DoctrineOrmTypeGuesser.php on line 25
  !! 14:00:50 CRITICAL [php] Fatal Error: During class fetch: Uncaught ReflectionException: Class Symfony\Component\Form\FormTypeGuesserInterface not found in /opt/releases/20190626075527/api/vendor/symfony/doctrine-bridge/Form/DoctrineOrmTypeGuesser.php:25
  !! Stack trace:
  !! #0 /opt/releases/20190626075527/api/vendor/composer/ClassLoader.php(444): include('/opt/releases/2...')
  !! Untitled #1 /opt/releases/20190626075527/api/vendor/composer/ClassLoader.php(322): Composer\Autoload\includeFile('/opt/releases/2...')
  !! Renaming "Entities" to "Entity" #2 [internal function]: Composer\Autoload\ClassLoader->loadClass('Symfony\Bridge\...')
  !! Untitled #3 [internal function]: spl_autoload_call('Symfony\Bridge\...')
  !! Same change for mapping files #4 /opt/releases/20190626075527/api/vendor/symfony/config/Resource/ClassExistenceResource.php(76): class_exists('Symfony\Bridge\...')
  !! Using ORM and MongoDB both in the same bundle. #5 /opt/releases/20190626075527/api/vendor/symfony/dependency-injection/ContainerBuilder.php(353): Symfony\Component\Config\Resource\ClassExistenceResource->isFresh(0)
  !! [Form] Outstanding patches for Choice/Collection fields #6 /opt/releases/20190626075527/api/vendor/symfony/dependency-injection/Compiler/AutowirePass.php(338): Sy ["exception" => Symfony\Component\Debug\Exception\FatalErrorException { â¦}]
  !!
  !! In DoctrineOrmTypeGuesser.php line 25:
  !!
  !! Error: During class fetch: Uncaught ReflectionException: Class Symfony\Comp
  !! onent\Form\FormTypeGuesserInterface not found in /opt/releases/201906260755
  !! 27/api/vendor/symfony/doctrine-bridge/Form/DoctrineOrmTypeGuesser.php:25
  !! Stack trace:
  !! #0 /opt/releases/20190626075527/api/vendor/composer/ClassLoader.php(444): i
  !! nclude('/opt/releases/2...')
  !! Untitled #1 /opt/releases/20190626075527/api/vendor/composer/ClassLoader.php(322): C
  !! omposer\Autoload\includeFile('/opt/releases/2...')
  !! Renaming "Entities" to "Entity" #2 [internal function]: Composer\Autoload\ClassLoader->loadClass('Symfony\
  !! Bridge\...')
  !! Untitled #3 [internal function]: spl_autoload_call('Symfony\Bridge\...')
  !! Same change for mapping files #4 /opt/releases/20190626075527/api/vendor/symfony/config/Resource/ClassExi
  !! stenceResource.php(76): class_exists('Symfony\Bridge\...')
  !! Using ORM and MongoDB both in the same bundle. #5 /opt/releases/20190626075527/api/vendor/symfony/dependency-injection/Con
  !! tainerBuilder.php(353): Symfony\Component\Config\Resource\ClassExistenceRes
  !! ource->isFresh(0)
  !! [Form] Outstanding patches for Choice/Collection fields #6 /opt/releases/20190626075527/api/vendor/symfony/dependency-injection/Com
  !! piler/AutowirePass.php(338): Sy
  !!
  !!
  !! cache:clear [--no-warmup] [--no-optional-warmers] [-h|--help] [-q|--quiet] [-v|vv|vvv|--verbose] [-V|--version] [--ansi] [--no-ansi] [-n|--no-interaction] [-e|--env ENV] [--no-debug] [--test-mode TEST-MODE] [--]
  !!
  !!
  Script @auto-scripts was called via post-install-cmd