SCOM does not properly groom all MT*_Log tables

UPDATE: This issue has been resolved in SCOM 2012 R2 UR7. I was asked to look at a very large OperationsManager database.  One of the MT*_Log tables had over 53 million rows.  This lead me to a bug in one of SCOM's grooming stored procedures. Background Whenever you discover a class instance in SCOM it is added…