Add more logging to histogram processing
Add more logging to histogram processing

This should help aid in debugging issues with histogram upload
processing.

R=f07c55753dac44d78e0294a1d64ea321baaa78f4@google.com, fancl@chromium.org

Change-Id: I75557ea902c2e172f6cf7a1fcceffa874a9bdb3b
Reviewed-on: https://chromium-review.googlesource.com/c/catapult/+/2105716
Auto-Submit: Dean Berris <34a37f59e4ade3cf49221306f04217acf3e86255@chromium.org>
Commit-Queue: Andrew Bennetts <f07c55753dac44d78e0294a1d64ea321baaa78f4@google.com>
Reviewed-by: Andrew Bennetts <f07c55753dac44d78e0294a1d64ea321baaa78f4@google.com>

catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult