kes Rework prune_volumes() code to take account of InChanger flag,

kes  Rework prune_volumes() code to take account of InChanger flag,
     and to handle recycling volumes going to the Scratch pool and
     current pool because the RecyclePool directive.
kes  Implement a better and more efficient db_get_query_dbids() to
     handle creating and passing back a list of DBIds.