fix copying data directory

src/csharp/Grpc.IntegrationTesting.Client/project.json

src/csharp/Grpc.IntegrationTesting.QpsWorker/project.json

src/csharp/Grpc.IntegrationTesting.Server/project.json

src/csharp/Grpc.IntegrationTesting.StressClient/project.json

src/csharp/Grpc.IntegrationTesting/project.json

templates/src/csharp/build_options.include