Merge pull request #7682 from apolcyn/add_runtime_nodes_back_in_ga

src/csharp/Grpc.Examples.MathClient/project.json

src/csharp/Grpc.Examples.MathServer/project.json

src/csharp/Grpc.Examples/project.json

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

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

...src/csharp/Grpc.Examples.MathClient/project.json.template

...src/csharp/Grpc.Examples.MathServer/project.json.template

templates/src/csharp/Grpc.Examples/project.json.template

...p/Grpc.IntegrationTesting.QpsWorker/project.json.template

...rpc.IntegrationTesting.StressClient/project.json.template

templates/src/csharp/build_options.include