set the route_collection_limit to 0 by default for BC

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | no
| Fixed tickets | https://github.com/symfony-cmf/RoutingBundle/issues/241 
| License       | MIT
| Doc PR        | -