Remove feature auto_alias because it is not fully implemented #21321
Description
Original pull request : #12526
@wouterj @xabbuh @nicolas-grekas @fabpot
The feature implement the CompilerPass AutoAliasServicePass see https://github.com/symfony/symfony/blob/master/src/Symfony/Component/DependencyInjection/Compiler/AutoAliasServicePass.php
Unfortunately it has never been wired. So it is not available in symfony.
Why do we keep this feature if it is not wired?