Less verbose logging

It's very difficult to diagnose the cause of a test failure in CI because of the very verbose logging which is almost always irrelevant to the cause of failure. A lot of the culprits come come from Helix, but some Pinot logging should be moved from WARN to DEBUG.

Start by reproducing the CI test-failure output and identifying which Helix messages and Pinot WARN logs make it unnecessarily verbose. The work is done when irrelevant logging is reduced without hiding information needed to diagnose test failures.

Written by the indexing model from the issue text.