Decide on default chunk interval(1hr?)

[arajkumar]

Currently our default chunk interval is 8 hr.

However in the recent conversations we started recommending 1hr chunk interval for better ingestion throughput. The same should reflect on the code as default instead of 8hr.

[ramonguiu]

@arajkumar we need to test the impact on query performance and maintenance jobs before we can move forward with this change