Improve isRunning() implementation for OrchestrationMetadata

Currently, isRunning() relies on the name, instanceId, and runtimeStatus parsed from the OrchestrationState returned over gRPC to determine whether the orchestration is running, however, there is also an Exists field on OrchestrationState that should also be considered, as runtimeStatus is populated from an enum with a default value.

This may also affect the implementation of isCompleted() and/or isInstanceFound()

Individua OrchestrationMetadata e i suoi punti di ingresso isRunning(), isCompleted() e isInstanceFound(), quindi segui come viene ricevuto OrchestrationState tramite gRPC. Verifica come vengono attualmente gestiti il campo Exists e il runtimeStatus predefinito, quindi aggiungi o aggiorna i test in modo che i metodi interessati distinguano correttamente le orchestrazioni esistenti da quelle non esistenti.