BackupReceiver survives cache shutdown

When the cache manager is stopped together with all caches, the static field BackupReceiverRepositoryImpl.backupReceivers is not cleaned up. When another cache manager is started and we try to XS replicate into this node, the request reaches BackupReceiver with references to the old, stopped cache. This instance has TERMINATED ComponentRepository without TransactionTable and this results in NullPointerException in BackupCacheUpdater.replayModificationsInTransaction.

When the cache is stopped, it should remove all references to it from the BackupReceiverRepositoryImpl.backupReceivers.