[FrameworkBundle] Improved controller class error

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | https://github.com/symfony/symfony/issues/11304
| License       | MIT
| Doc PR        | 
@guilhermeblanco But the `_route` part is in the actual `HttpKernel` component - where `symfony/routing` is only a "dev" requirement.