remove all exception handling from legacyRouteListener. 

Forces all Exceptions to be handled by the same Listener (\Zikula\Bundle\CoreBundle\EventListener\ExceptionListener) refs #1789

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| Refs tickets  | #1789
| License       | MIT
| Doc PR        | -
And here.