Revert "dockerfiles/go: go install from GOPATH and remove bash from CMD"

tools/dockerfile/grpc_go/Dockerfile

@@ -37,8 +37,8 @@ RUN go get google.golang.org/grpc
 ADD service_account service_account
 
 # Build the interop client and server
-RUN go install google.golang.org/grpc/interop/client
-RUN go install google.golang.org/grpc/interop/server
+RUN cd src/google.golang.org/grpc/interop/client && go install
+RUN cd src/google.golang.org/grpc/interop/server && go install
 
 # Specify the default command such that the interop server runs on its known testing port
-CMD ["server", "--use_tls=true", "--port=8020"]
+CMD ["/bin/bash", "-c", "cd src/google.golang.org/grpc/interop/server && go run server.go --use_tls=true --port=8020"]