[3.0] Remove *.class parameters in bundles

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | yes
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11881
| License       | MIT
| Doc PR        | none

Remove the *.class parameters in all bundle settings.

see: https://github.com/symfony/symfony/issues/11881
@mayeco you haven't changed the code in the DI extension to change the service class.

Even though the old API will be removed from 3.0, we should keep the code working in the meantime