Alias the workflow registry

[loic425]

Q	A
Bug fix?	yes (will be)
New feature?	no
BC breaks?	no
Deprecations?	no
Related tickets
License	MIT

See these different versions
5.4
6.1
6.2

On 6.2, the 'workflow.registry' is an alias of '.workflow.registry' instead of being the id itself.

[vvasiloi]

Is there a way to not use the registry and still provide a good DX?

[vvasiloi]

After discussing with @loic425 in private we came to the conclusion that we should try to avoid usage of the registry.
The alias was deprecated and the workflow registry is considered an internal service and it's usage is discouraged by the Symfony team.
Sources:

• [Workflow] Mark registry as internal and deprecate the service symfony/symfony#46000
• https://symfony.com/doc/current/workflow.html

I'll come up with an alternative proposal to this PR.