CDAP-640 - Metrics Increase RunId max Entries 

This PR is to increase the for max entries for runId in Metrics Entity Table from (2^16) to (2^32) 

While testing this, we figured an issues with our levelDB getRow implementation, where the limit was ignored and due to that we were scanning the entire table for a simple incrementAndGet. This PR contains the fix for that as well.

Edit: See @abaranau comment. This PR has been changed, to recycle and use the old runId once we reach the 65k limit, than increase the runID range to 2^32.
https://issues.cask.co/browse/CDAP-640
add a comment saying that should not happen for anything other than runId. And runId is fine to reset to 0, since metrics for old runIds will be truncated earlier than we start re-using IDs