Updated service definition to support Messenger 5.1

[Nyholm]

I have a PR open to Symfony to move the Doctrine transport to a new package. See symfony/symfony#35422

If my Symfony PR is merged, this PR makes sure that DoctrineBundle is compatible with Symfony Messenger 5.1 without any deprecation notices.

This PR could also be cherry-picked to 1.x branch.

[Nyholm]

Thank you for the review.

My PR got merged in Symfony so I removed WIP on this PR. This PR is not "on hold" anymore.

[SenseException]

Nice. After adding (a) testcase(s), this should be fine from my point of view.

[Nyholm]

Thank you.

Could you give me some guidance how I can test both outcomes of if (! class_exists(DoctrineTransportFactory::class))?

[SenseException]

The build process is installing composer packages differently for many use cases. One is a PHP 7.1 using --prefer-lowest. If there's an installation without a Messenger component, another path will be covered. You'll find an example for the Messenger component here:
https://github.com/doctrine/DoctrineBundle/blob/master/Tests/DependencyInjection/DoctrineExtensionTest.php#L660

[ostrolucky]

This looks OK to me

Fixed

[alcaeus]

Thanks @Nyholm!

[alcaeus]

And I just realised I merged this without squashing commits. Oh well 🤷‍♂️