[CF-294] Fix getting nonexistent instance for deploy_instance function
[CF-294] Fix getting nonexistent instance for deploy_instance function

Check that failed instance exists.

SVilgelm/CloudFerry,MirantisWorkloadMobility/CloudFerry,mgrygoriev/CloudFerry,mgrygoriev/CloudFerry,mgrygoriev/CloudFerry,MirantisWorkloadMobility/CloudFerry,SVilgelm/CloudFerry,MirantisWorkloadMobility/CloudFerry,SVilgelm/CloudFerry,MirantisWorkloadMobility/CloudFerry,mgrygoriev/CloudFerry,SVilgelm/CloudFerry