Registry - WorkflowRestService process -> force index update

[rsoika]

In case of processing a workitem with a given $uniqueid the registry WorkflowRestService should force an index update.

A delay caused by the asynchronous indexer can produce unexpected results. E.g. if a client creates and updates the same workitem in short time (<100ms)

With forcing an index update the side effect of outdated index can be covered.