Memory Leak on execution of BackupAware operation that runs into a timeout.

Fixed #1559

It is fixed by always removing backup calls and remote calls on future completion
so there is no garbage. In the future we need to have a better system so that the
operation service will cleanup calls itself.
Merge pull request #1560 from pveentjer/fix/3-maintenance/oome-on-operationtimeout

Memory Leak BackupAware operation and timeout