[DIC] Fixed: anonymous services are always private

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        |

This PR fix a regression introduce by https://github.com/symfony/symfony/commit/33c91f9be8e48fb085ab28019716eddc924c5904#diff-c68f5120ea7d664e07e96cc40bdf6295L268

* First commit is just about CS
* Second commit really fix the regression (see only this diff to easily understand)

ping @sandermarechal @romainneutron