Tear down DBAccess on stopped instead of on release

Related to a reported issue in which a database is unable to be deleted due to our internal classes holding a reference to them. For reasons still unknown, the replicator is not being torn down in a timely fashion which causes this problem. So instead of waiting for it to be torn down before getting rid of the DB handles, do so immediately upon stopped. The class holding these references is designed to be single shot anyway (i.e. if it is needed again after stop, a new one is created) so it doesn't matter much from the class' standpoint where we do this.