Set Kafka Streams default commit interval to 5000ms

Currently, we configured a default commit interval of 100 ms. Kafka Streams default setting is 30000ms for at-most once (default) and 100ms for exactly once. A commit interval of 30000 ms has the big disadvantage that stateful processor nodes forward results only every 30s, which is impractical for short-running jobs as our benchmarks

The default commit interval of "normal" Kafka consumers is 5000ms, which is hence also used by all other stream processing engines.

Setting the default commit interval to 5s improves comparability between streaming engines and seems to be a reasonable tradeoff between the configs for at-most once exactly once.