Initialize bad stream eagerly rather than lazily

[fblundun]

https://github.com/snowplow/kinesis-s3/blob/master/src/main/scala/com.snowplowanalytics.snowplow.storage.kinesis/s3/sinks/KinesisSink.scala#L77

Originally this was so that the app wouldn't create the bad stream until it became necessary. But now that we have snowplow/snowplow#1529, the lazy val just means that if the stream doesn't exist, that error won't be caught immediately.

[alexanderdean]

Makes sense!