Add REMOVED state for collections no longer active in ACE

Add REMOVED state for collections in ACE that are no longer active.

Current Behavior

When deleting a collection, node admins will backup the ACE database and then deleted the collection from the database. Those DELETED collections will be lost from the current ACE database.

Expected behavior

Those DELETED collections will be retained in ACE DB so that we don't need to backup ACE database specifically for those deleted collections. A new state called REMOVED will be added to flag those collections that mean to be deleted. And in column state of table collection, character 'R' should be persisted to indicate a collection with REMOVED state.

Acceptance

Collections with REMOVED state will be excluded from future auditing, and make sure the change won't interrupt any functions and features in ACE.