fix: enable output rails streaming explicitly

[Pouyanpi]

Refactored the conditional checks to enable output streaming configuration based on the self.config.rails.output.streaming.enabled flag. This change ensures that the streaming handler is correctly utilized when output streaming is enabled in the configuration.

[trebedea]

Looks good.
@Pouyanpi - it would be nice if we could have a test if future changes break the correct behavior. If it's not simple to add it, we can merge without it.

[Pouyanpi]

@trebedea tests added 👍🏻