change logging for through_seqno_service to TRACE

Currently log messages in through_seqno_service are printed out in DEBUG level. There are so many log messages that it filled a log file in the matter of seconds. This seriously reduced the usefulness of DEBUG level logging.

One way to fix this is to change these log messages to TRACE level. This way DEBUG level becomes more usable and can be used to debug things like conflict resolution issues. If there are issues with through_seqno_service, we can quickly flip TRACE level logging on and then off to get some hint of how things are. If needed, we can increase the stats collection interval, which affects how often through_seqno service is called, at runtime to reduce the TRACE logging by through_seqno service to make them more manageable when debugging.