Only make the Swift Xcode project (instead of a full Xcode build) on macOS CI, as that is covered by the Carthage build already.
Only make the Swift Xcode project (instead of a full Xcode build) on macOS CI, as that is covered by the Carthage build already.

grpc/grpc-swift,grpc/grpc-swift,grpc/grpc-swift,grpc/grpc-swift,grpc/grpc-swift